Library apparatus and a method for assembly thereof

ABSTRACT

A library apparatus having components permitting accurate and straightforward assembly. The library apparatus includes respective cell, drive, accessor and passage units, each having box shaped housings including a connection mechanism. A coupling couples the housings of the passage units with the other units. Other features of the library apparatus include a reference mark on the accessor unit which permits a transport mechanism in the passage unit to correct positional errors of the transport mechanism to other components.

This application is a continuation of application Ser. No. 08/607,898filed on Feb. 27, 1996, abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a library apparatus with cells forstoring cartridges accommodating memory media therein and a method forassembling the same.

The library apparatus has a plurality of cells for storing cartridges,such as magnetic tape cartridges or optical disk cartridges,accommodating information memory media therein. The cartridge stored inone cell selected from the plurality of cells is loaded to a drive unitin the library apparatus. Information is recorded on and regeneratedfrom the medium accommodated in the cartridge by the drive unit.

Further, it is desirable that the entry of a cartridge into the libraryapparatus is easy for the operator.

Recently, the demand for a large capacity library apparatus hasincreased. It is desirable that the library apparatus has a smallerinstallation area and a larger capacity capable of accommodating alarger number of cartridges.

Also, the library apparatus is preferably of an unattended systemwherein high reliability is indispensable; for example, restoration iseasy if the power source is shut-down.

2. Description of the Invention

A library apparatus such as a magnetic tape library includes a cartridgeaccess station (CAS) for carrying out the entry and exit of a cartridgeaccommodating a memory medium, a cell drum having a plurality of cells,each accommodating cartridges, a drive unit for carrying out therecording on and regeneration from the memory medium in the cartridge,and an accessor for transporting the cartridge between the accessstation, the cell drum and the drive unit.

The accessor carries a gripper mechanism for gripping a cartridge and areciprocation mechanism for reciprocating the gripper mechanism. Also, anumber of printed boards for controlling the gripper mechanism and thereciprocation mechanism are mounted thereon.

The entry operation of a new cartridge into the library apparatus iscarried out in such a manner that the operator inserts the cartridgeinto an entry opening provided in a cartridge access station. When thecartridge is inserted into the entry opening, an accessor grips thecartridge and conveys the same to a selected cell in the cell drum. Anaddress of the cell to which the cartridge is to be stored is known byreading a bar code label, attached to the cartridge by a bar codereader.

The library apparatus is used for storing data for calculations executedby a host computer and the library apparatus is generally installed in aroom in a building in the same way as the host computer. Accordingly,the library apparatus must be easily carried into the building andassembled in a building.

However, since the size of the library apparatus is limited by the sizeof an elevator provided in the building, the number of cartridges to beaccommodated in the library apparatus is also limited.

Of course, it is possible to convey the library by the elevator whiledisassembling the library apparatus into individual parts. In such acase, however, a longer time is necessary to accurately assemble theindividual parts. Also, since accurate assembly cannot be expected inthe building site, it is impossible to provide a smaller cell pitch andthe cartridge-integration density cannot be very high.

On the other hand, since a cell used for the library apparatus has anexclusive structure for a cell drum or a magazine, there are problems inthat the number of rows and stages of cell are unchangeable and theproduction cost of a cell becomes higher.

In addition, in the conventional library apparatus, it is necessary toinsert cartridges one by one into the entry opening of the cartridgeaccess station, whereby a longer time is required for the entry of alarge number of cartridges into the library apparatus.

Also, there are problems in that a longer time is necessary until theaccessor conveys a cartridge to a selected cell, because an address ofthe cell wherein the cartridge is to be stored is unknown unless the barcode label has been read by the bar code reader mounted on the accessor.

Also, in the conventional library apparatus, it is necessary to convey acartridge inserted therein to a cell in a shelf for accommodatingcartridges within the library apparatus.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide a libraryapparatus capable of accommodating a large number of cartridges thereinand being easily assembled in a shorter time period, and a method forassembling such a library apparatus.

A second object of the present invention is to provide a libraryapparatus capable of reducing the production cost of a cell, and a cellfor storing cartridges.

A third object of the present invention is to provide a libraryapparatus including a cell unit which also can be used for theproduction of cells of a cartridge magazine.

A fourth object of the present invention is to provide acartridge-accommodation cell capable of variously changing the number ofrows and/or stages.

A fifth object of the present invention is to provide a libraryapparatus capable of reducing the time necessary for the entry of alarge number of cartridges to accommodation shelves of the libraryapparatus.

A sixth object of the present invention is to provide a libraryapparatus in which it is unnecessary to convey a large number ofcartridges inserted at one time into the library apparatus toaccommodation shelves with cells for accommodating cartridges.

A seventh object of the present invention is to provide a libraryapparatus capable of reading bar code labels in a shorter time period,attached to a number of cartridges inserted into the library apparatus.

According to the present invention, since the library apparatus isconstituted of drum units, accessor units, passage units and driveunits, the transportation thereof becomes easy. The more drum units, themore cartridges to be accommodated in the library apparatus. Also, sincethe library apparatus is structured by the coupling of units, theassembly thereof becomes easy.

As a cell in the library apparatus is formed of the combination of aleftside cell unit, a central cell unit and a rightside cell unit, it ispossible to reduce the production cost of the cell. The libraryapparatus includes a cell unit which also can be used for the productionof cells of a cartridge magazine.

Further, according to the present invention, it is possible to save theoperation time necessary for the entry of a number of cartridges toaccommodation shelves of the library apparatus. Also, according to thepresent invention, since the magazine shelf can be regarded as part ofanother accommodation shelf, it is unnecessary for the accessor toimmediately transfer a cartridge after the entry of cartridge. Further,since a bar code reader is provided for reading bar code labels on alarge number of entry cartridges, a time necessary for the transfer ofthe cartridges can be saved. Also, according to the present invention,the simultaneous entry of a large number of cartridges is possible bythe use of a magazine, and the immediate transfer of the cartridges isunnecessary after the entry.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more clearly understood from thedescription as set forth below with reference to the accompanyingdrawings, wherein;

FIG. 1 is a diagrammatic see-through perspective view of a libraryapparatus according to the present invention;

FIG. 2 is a perspective view illustrating a system of the libraryapparatus according to the present invention;

FIG. 3 is a side view of an accessor;

FIG. 4A a side view for explaining an X-directional motion mechanism forthe accessor;

FIG. 4B is a partial plan view for explaining a Y-directional motionmechanism for the accessor;

FIG. 5 is a diagrammatic perspective view of a hand assembly;

FIG. 6 is a side view of an accessor unit;

FIG. 7 is a back view of the accessor unit;

FIG. 8 is a perspective view for explaining the coupling between areference unit and a drive unit;

FIG. 9 is a perspective view for explaining a cartridge mount cell of atape drive unit within the drive unit;

FIG. 10 is a side view for explaining an automatic cartridge-replacementmechanism within the tape drive unit:

FIG. 11 is a side view of a manual mount cell used as means for storingcartridges;

FIG. 12 is a plan view of a cartridge feeder;

FIG. 13 is a side view of a cartridge feeder;

FIG. 14A is a plan view for explaining a passage unit;

FIG. 14B is a side view for explaining a passage unit;

FIG. 15 is a perspective view of the passage unit;

FIG. 16 is a wiring diagram for explaining the connection of signalcables in the passage unit and the connection thereof with the drumunit;

FIG. 17 is a view illustrating the coupling between the drum unit andthe passage unit;

FIG. 18 is a plan view of the drum unit;

FIG. 19 a side sectional view of the drum unit;

FIG. 20 is a side sectional view of a coupling mechanism between upperand lower units of the drum unit;

FIG. 21 is a perspective view for illustrating a method ofphase-alignment of the coupling mechanism;

FIG. 22 is a side sectional view of a coupling area of the couplingmechanism;

FIG. 23 is a top view of a drum unit with a DEE door;

FIG. 24 is a side sectional view of the drum unit with the DEE door;

FIG. 25 is the illustration for explaining the relationship between ascanning beam of a bar code reader and a cartridge surface on which abar code label is attached;

FIG. 26 is a front view of an inclination adjustment mechanism for thebar code reader;

FIG. 27 is a bottom view of the inclination adjustment mechanism for thebar code reader;

FIG. 28 is a block diagram of a control circuit including a bar codereader control portion;

FIG. 29 is a flow chart for the adjustment operation of a readingposition of the bar code reader;

FIG. 30 is the illustration for explaining a master bar code label;

FIG. 31 is a flow chart for the reading operation of the bar codereader;

FIG. 32 is the illustration of wave shapes for explaining theposition-correction operation of the bar code reader;

FIG. 33 is a flow chart for the operation for positioning the bar codereader at a position for reading a cartridge in a central row;

FIG. 34 is a flow chart for the operation for positioning the bar codereader at a position for reading a cartridge in a rightside row;

FIG. 35 is a flow chart for the operation for positioning the bar codereader at a position for reading a cartridge in a leftside row;

FIG. 36 is a side view of a cartridge-detection mechanism provided inthe drum unit with the DEE door;

FIG. 37 is a front view of the cartridge-detection mechanism provided inthe drum unit;

FIG. 38 is a detailed view for explaining a mechanism for cleaning thecartridge-detection mechanism;

FIG. 39 is a perspective view of part of the cleaning mechanism shown inFIG. 38;

FIG. 40 is a side view of a structure of the drum unit using a DEEmagazine;

FIG. 41 is a diagrammatic perspective view showing a structure of themagazine and a magazine shelf;

FIG. 42A is a view for explaining the operation for loading the magazineinto the magazine shelf of the drum unit;

FIG. 42B is a view showing a state wherein the magazine is loaded in themagazine shelf of the drum unit;

FIG. 43A is a plan view illustrating a detailed structure of themagazine;

FIG. 43B is a front view illustrating a detailed structure of themagazine;

FIG. 43C is a back view illustrating a detailed structure of themagazine;

FIG. 44 is a perspective view of a leftside cell unit;

FIG. 45 is a perspective view of a central cell unit;

FIG. 46 is a perspective view of a rightside cell unit;

FIG. 47 is a perspective view of a magnetic tape cartridge;

FIG. 48 is an illustration for explaining a method for manufacturing thelibrary apparatus shown in FIG. 2;

FIG. 49A is a bottom view of the reference unit for explaining a methodfor installing the reference unit;

FIG. 49B is a side view of the reference unit for explaining a methodfor installing the reference unit;

FIG. 50 is the illustration for explaining a method for coupling thepassage unit to the reference unit;

FIG. 51 is the illustration for explaining a method for coupling theaccessor unit to the passage unit;

FIG. 52 is the illustration for explaining a method for coupling thedrum unit to the passage unit;

FIG. 53 is the illustration for explaining a method for coupling twodrum units to each other;

FIG. 54 is the illustration for explaining a method for mounting a toprail;

FIG. 55 is a diagram for illustrating one example of a structure ofhardware of the library apparatus;

FIG. 56 is a diagram for illustrating one example of a structure ofhardware of an accessor controller;

FIG. 57 is a diagram for illustrating one example of a structure ofhardware of a machine controller;

FIG. 58A is the illustration for explaining a sensor provided in theaccessor;

FIG. 58B is a partial enlarged view for explaining the sensor and asensor flag provided in the accessor;

FIG. 59 is part of a flow chart for the explanation of the operation forcorrecting a position of the accessor;

FIG. 60 is part of a flow chart for the explanation of the operation forcorrecting a position of the accessor;

FIG. 61 is part of a flow chart for the explanation of the operation forcorrecting a position of the accessor;

FIG. 62 is part of a flow chart for the explanation of the operation forcorrecting a position of the accessor;

FIG. 63 is a plan view for the explanation of the operation forcorrecting a position of the accessor;

FIG. 64A is a plan view for the explanation of the operation forcorrecting a position of the accessor;

FIG. 64B is a side view for the explanation of the operation forcorrecting a position of the accessor;

FIG. 65 is a side view for the explanation of the operation forcorrecting a position of the accessor;

FIG. 66 is a perspective view for explaining a positional correctionflag;

FIG. 67 is the illustration for explaining the operation for measuring aposition;

FIG. 68 is a first half of a flow chart of the operation for correctingthe sensitivity of X-directional sensor;

FIG. 69 is a latter half of a flow chart of the operation for correctingthe sensitivity of X-directional sensor;

FIG. 70 is a first half of a flow chart of the operation for correctingthe sensitivity of Y-directional sensor;

FIG. 71 is a latter half of a flow chart of the operation for correctingthe sensitivity of Y-directional sensor;

FIG. 72 is a first half of a flow chart of the operation for correctingthe sensitivity of Z-directional sensor;

FIG. 73 is a latter half of a flow chart of the operation for correctingthe sensitivity of Z-directional sensor;

FIG. 74 is the illustration for explaining the theoretical arrangementof addresses allocated to each of the units in the library apparatusshown in FIG. 1;

FIG. 75 is the illustration of the addresses to be allocated to the drumunit;

FIG. 76 is the illustration for explaining control values of a machinecontroller;

FIG. 77 is the illustration for explaining a coordinate system of areference cell in the drum unit carrying the DEE magazine;

FIG. 78 is the illustration for representing a relationship betweencenters of a real position and a reference position of the referencecell;

FIG. 79 is the illustration for representing a relationship between amark for correcting a position and a starting point for the measurement;

FIG. 80 is a flow chart for explaining the operation of a machinecontroller roller;

FIG. 81 is part of a flow chart for processing the measuring operationof a positional correction value;

FIG. 82 is part of a flow chart for processing the measuring operationof a positional correction value;

FIG. 83 is part of a flow chart for processing the measuring operationof a positional correction value;

FIG. 84 is part of a flow chart for detecting the presence of amagazine;

FIG. 85 is part of a flow chart for detecting the presence of amagazine;

FIG. 86 is part of a flow chart for detecting the presence of amagazine;

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a see-through perspective view of a library apparatus.

In FIG. 1, two cartridge access stations (CAS) 5 are provided on thefront side of a leftside accessor unit 7 and a rightside accessor unit 9of the library apparatus 2, respectively.

Each of the cartridge access stations 5 has a cartridge entrance 6 and acartridge exit 8. The cartridge entrance 6 and the cartridge exit 8 arerotatable by 180° on the vertical axes thereof.

Drum units 10a and 10b have cell drums 15a and 15b, respectively, eachhaving a plurality of cells. Each of the cell drums 15a and 15b consistsof seven cell segments 17a through 17f. Each of the cell segments 17athrough 17f in the respective cell drum 15a and 15b has cells arrangedin three rows and n stages. Each of the cells stores a cartridge foraccommodating a magnetic tape therein. Each cartridge is a Type 13480magnetic tape cartridge. Four drive units 12a, 12b, 12c and 12d carryout the recording/regeneration of information to the magnetic tapeaccommodated in the cartridge as a memory medium. Each of the driveunits 12a, 12b, 12c and 12d has a plurality of tape drive units. Forexample, four tape drive units are provided in the respective drive unit12a, 12b, 12c or 12d. Each of the tape drive units has a cartridgeentry/exit opening. The cartridge entry/exit opening is sloped to aplane including X-axis and vertical to Y-axis by an angle of 5.5°.

A control printed circuit board is provided in a housing 4, forcontrolling the cartridge access stations 5, the drum units 10a and 10b,the drive units 12a, 12b, 12c and 12d and two accessors 14.

The accessor 14 is provided with a handle assembly 16 movableupward/downward (in the arrowed direction Y in the drawing) along avertical column 18. The accessor 14 is movable in the lateral direction(in the arrowed direction in the drawing) along a guide rail (X rail)20. In such a way, the accessor 14 is an X-Y motion mechanism.

FIG. 2 is a see-through perspective view of a system of the libraryapparatus.

In FIG. 2, the respective units are arranged in the library apparatuswhile using the reference unit 11 as a reference. The reference unit 11is positioned at the center of the library apparatus 2. The accessorunit 9 is positioned at the righthand end thereof. The accessor unit 7is positioned at the lefthand end thereof. Passage units 13 are arrangedbetween the reference unit 11 and the accessor unit 7. The number of thepassage units 13 varies in accordance with that of the drum units 10arranged between the reference unit 11 and the accessor unit 7. Sincefour drum units 10 are arranged in the library apparatus 2 shown in FIG.2, the number of the passage units 13 is two. Also, the number of thepassage units 13 arranged between the reference unit 11 and the accessorunit 9 is two, because the number of the drum units 10 arranged betweenthe reference unit 11 and the accessor unit 9 is four. The drum unit 10ais provided with a DEE door 64 for allowing the operator to carry outthe direct entry/exit of the cartridge to a cell of the cell drum 15.The drum unit 10b is provided with a DEE door (not shown) for allowingthe entry/exit of a magazine to a magazine shelf of a magazine drum 175.The passage unit 13 can be used as a reference box for coupling therespective units. The passage unit 13 holds the X rail 20. A top rail 21is provided for guiding the accessor 14. The top rail 21 is fixed to thedrum unit 10.

FIG. 3 is a side view of the accessor.

In the drawing, the hand assembly 16 is carried on a supporting base 24movable upward/downward along a guide rail 22 fixed to the verticalcolumn 18 of the accessor 14. The supporting base 24 carries a motor 25thereon. Further, the supporting base 24 carries a printed circuit board29 having a control circuit for controlling the motor 25. The supportingbase 24 moves in the Y-axis direction together with the motor 25 and theprinted circuit board 29 along the guide rail 22.

When the motor 25 is driven, a mount base 27 of the hand assembly 16turns on the vertical axis (an axis parallel to the Y-axis) via a timingbelt 26 wrapped around an output shaft of the motor 25. That is, themotor 25, the hand assembly 16 and the mount base 27 constitute amechanism for moving the cartridge to θ-direction.

The mount base 27 moves together with the printed circuit board 29carrying a control circuit for controlling the hand assembly 16, a motorand a sensor incorporated therein. The printed circuit board 29 carriesthe control circuit for controlling the motor for rotating the handassembly 16 on an axis of the base 27.

The vertical column 18 holds a supporting plate 23 for supporting aroller 31 guided by the top rail.

FIGS. 4A and 4B are the illustration for explaining an X-directionalmotion mechanism.

With reference to FIG. 4A, the vertical column 18 holds a Y-axis motor46 for reciprocating the supporting base 24 along the guide rail 22. Thevertical column 18 is held by a rail base 32. The rail base 32 rotatablycarries rollers 34a and 34b and rollers 36a and 36b. The rollers 34a and34b nip the X rail 20 at one end of the rail base 32. The rollers 36aand 36b nip the X rail 20 at the other end thereof. A roller 38 is heldby the rail base 32 to be in contact with the X rail 20. The roller 38constitutes a frictional force adjusting mechanism.

An X-axis motor 42 is provided for moving the rail base 32 along the Xrail 20. The X axis motor 42 is fixed to the rail base 32. A pinion 41is fixed to an output shaft of the X-axis motor 42. The pinion 41 ismeshed with a rack (not shown) attached to a housing to which the X railis fixed.

A printed circuit board 40 is fixed to the rail base 32. The printedcircuit board 40 is connected to a controller (not shown) providedwithin the housing 4 via an X cable 44. The printed circuit board 40carries a control circuit for controlling the Y-axis motor 46 and theX-axis motor 42.

A position of an end portion 32b of the base 32 at which the rollers 34aand 34b are held is separated by a distance L from a center portion 32aof the base. In other words, as shown in FIG. 4B, the end portion 32b islocated outside a circle of radius R having a center at a rotationcenter O of the hand assembly 16. The end portion 32b and the roller 34aare located at positions not interfering with a motion range of the handassembly. The rail base 32 has a long wheel base. The Y-directionalmotion range of the hand assembly 16 is larger than that wherein the endportion 32b is positioned inside the motion range of the hand assembly16. Accordingly, it is possible to increase the number of stages of thecells in the cell segment of the cell drum 10a and 10b, resulting in theincrease in the number of cartridges to be accommodated therein.

FIG. 5 is a diagrammatic perspective view of the hand assembly 16.

With reference to FIG. 5, the hand assembly 16 is provided with a base28. The base 28 carries thereon a hand unit 130 having an upper hand 146and a lower hand 148 to be movable between a forward position and abackward position.

The base 28 is rotatably mounted to a rotary shaft 160 held by the base27. The base 27 carries a motor (not shown) for rotating the base 28carrying the hand unit 130 on the rotary shaft 160. In other words, thebase 28 carrying the hand unit 130 is rotatable on the rotary shaft 160between a first inclined position and a second inclined positioninclined at 5.5° and 12° relative to the base 27, respectively.

A motor 132 is mounted to a rear end of the base 28, for moving the handunit 130. A pulley, not shown, is fixed to an output shaft of the motor132. A pulley 134 is rotatably mounted to a front end of the base 28. Atiming belt 136 is wrapped around the pulley fixed to the output shaftof the motor 132 and the pulley 134. The timing belt 136 is coupled tothe hand unit 130.

When the motor 132 is driven, the torque of the motor is transmitted tothe hand unit 130 via the timing belt 136 to operate the hand unit 130.The hand unit 130 is engaged in a sliding motion between the forwardposition and the backward position along a guide rail 138 provided onthe base 28.

Since the timing belt is coupled to the hand unit 130, the hand unit 130moves between the forward position and the backward position when themotor 132 is driven, as shown by an arrow A, while being guided by theguide rail 138.

A sensor 162 is provided at an end of the base 28 of the hand assembly16. The sensor 162 is used for detecting the presence of the cartridgewithin the cell. As shown in FIG. 1, a sensor 163 is provided on therail base 32 of the accessor 14. The sensor 163 is used for detecting aposition flag 165 provided on the accessor unit 9.

FIG. 6 is a side view of the accessor unit 9. The accessor unit 7 hasthe same structure as the accessor unit 9, except that the accessor 14is attached to the accessor unit 7 in reverse to in the accessor unit 9.

Accordingly, the structure of the accessor unit 9 will be solelyexplained with reference to FIG. 6. In FIG. 6, the X rail 20 is fixed toa base 51. The base 51 is supported on the floor surface by footings 33.The base 51 holds pillars 35a and 35b. The pillars 35a and 35b arecoupled with each other by a reinforcing bar 37 and the upper ends ofthe pillars are fastened together by a top panel 39. A cover 43 isattached above the top panel 39. An end surface 51a of the base 51 isused as a reference plane for the coupling with the passage unit 13shown in FIG. 2.

FIG. 7 is a back view of the accessor unit.

With reference to FIG. 7, the X rail 20 held by the base 51 of theaccessor unit 9 is nipped by the rollers 36a and 36b supported by therail base 32. The vertical column 18 is attached to the rail base 32. Aunit including a motor 46 is fixed the vertical column 18, for movingthe hand assembly 16 upward and downward along the guide rail 22 (seeFIG. 6) of the vertical column 18. An electromagnetic brake (of a drytype TB/TBK manufactured by Miniature Bearing K.K.) 502 is fixed to oneend of an output shaft 46a of the motor 46. The electromagnetic brake502 allows the output shaft 46a of the motor to freely rotate when anelectric source for supplying a power to the motor 46 is switched on,while inhibits the rotation thereof when the electric source is switchedoff. The output shaft 46a of the motor 46 is coupled to a pulley 506 viaa belt 504. The torque of the pulley 506 is transmitted to a pulley 510fixed to a shaft 508 common to the pulley 506. A torque of the pulley510 is transmitted to the hand assembly 16 via a belt 514 wrapped aroundthe pulley 510 and a pulley 512 rotatably held on a shaft 516 supportedby the vertical column 18. The belt 514 is fixed to the base 24 (seeFIG. 4A) of the hand assembly 16.

An arm 520 is attached to a lower end of the vertical column 18, forsupporting an elastic stop 518 made, for example, of Neoprene rubber.Also, another arm 524 is attached to the lower end of the verticalcolumn 18, for supporting an elastic stop 522 made, for example, ofNeoprene rubber. These elastic stops 518 and 522 act as a stop for thehand assembly 16 when the motor 46 is out of control.

The hand assembly 16 can be secured on the vertical column 18 due to thebraking action of the electromagnetic brake 502 even if the supply ofthe electric power for the library apparatus 2 is interrupted. If theelectromagnetic brake 502 were not provided, the hand assembly 16 wouldfall down due to gravity to collide with the elastic stop 518. Such acollision between the hand assembly 16 and the elastic stop 518 can beavoided by providing the electromagnetic brake 502 even when theinterruption of the power supply occurs, whereby the falling of thecartridges, from the hand assembly, can be prevented.

FIG. 8 is an illustration for explaining a method for coupling thereference unit 11 and the drive units. In FIG. 8, the reference unit 11includes a base 530 and four pillars 532. The pillars 532 are coupled toa top panel 534 at the upper ends thereof. The reference unit 11 of sucha structure is used as a reference box. The passage unit 13 is attachedto the base 530 of the reference unit 11. The passage unit 13 isprovided with side panels 536a and 536b constituting a reference planeto be contiguous to the reference plane of the drum unit as describedwith reference to FIG. 2. An end surface 538 of the passage unit 13defines a reference plane to be contiguous to those of the other passageunits or the reference unit 11.

The drive unit 12 is coupled to the reference unit 11. Four tape driveunits 540 are provided in the drive unit 12. The drive unit 12 hasmounting members 542, while the reference unit 11 has a pair of mountingmembers 544 on the opposite sides thereof. The mounting members 542 ofthe drive unit 12 are fastened to the mounting members 544 of thereference unit 11 with screws 546. On the other side of the referenceunit 11 opposite to the drive unit 12, another drive unit 12 is coupled.The coupling between the reference unit 11 and the latter drive unit 12is carried out by fastening the mounting members 544 of the referenceunit 11 to the mounting members 546 of the latter drive unit 12 byscrews.

FIG. 9 is the illustration for explaining a cartridge mount cell of thetape drive unit within the drive unit.

A structure of a single tape drive unit 540 within the drive unit 12shown in FIG. 8 is illustrated in FIG. 9. Any of the other tape driveunits 540 has a similar structure.

With reference to FIG. 9, the tape drive unit 540 includes a tape drive550 for carrying out the recording/regeneration of information to themagnetic tape accommodated in the cartridge and a cartridge feeder unit552 for carrying out the entry/exit of the cartridge to the tape driveunit 550. In the cartridge feeder unit 552, one of a manual mount cell554 and an accessor mount cell 556 is selectively mounted to a housing558. The manual mount cell 554 or the accessor mount cell 556 isinserted through an opening 560 of the housing 558. Apertures 562 areformed on the housing 558 in the vicinity of the opening 560, forfastening the mount cell 554 or 556 with screws.

The manual mount cell 554 is provided with mounting members 564a and564b. The mounting members 564a and 564b have apertures for fasteningthe manual mount cell 554 to the housing 558 of the cartridge feederunit 552 by screws. The aperture 566a is open to the outside at one endthereof. The manual mount cell 554 is fastened to the housing 558 byscrews after being inserted into the opening 560 of the housing 558.

The manual mount cell 554 has cells 568 within a housing 554a, arrangedin twelve stages for accommodating cartridges. Since the insertion ofthe cartridge to the cell 568 is manually carried out by the operator,an arrangement pitch of the cell 568 in the manual mount cells 554 canbe reduced.

On the other hand, the accessor mount cell 556 has cells 570a and 570barranged in two stages, for accommodating the cartridge therein. Each ofthe cells 570a and 570b are formed by rack plates 572 in a housing 556aof the accessor mount cell 556. The cell 570a is an entry cell forinserting a cartridge by the accessor 14 described with reference toFIG. 1. The cell 570b is an exit cell for retaining a cartridge to bedischarged from the cartridge feeder unit 552. The cartridge retained inthe exit cell 570b is taken out by the accessor 14.

The accessor mount cell 556 is provided with mounting members 574a and574b. The mounting members 574a and 574b have apertures 576 and 576aformed at positions coinciding with those of the apertures 562 in thehousing 558 of the cartridge feeder unit 552. The aperture 576a is opento outside at one end thereof. The accessor mount cell 556 is fastenedto the cartridge feeder unit 552 by screws via the mounting members 574aand 574b.

As described above, the drive unit 12 explained with reference to FIG. 8is provided with the tape drive unit 540 carrying either one of themanual mount cell 554 and the accessor mount cell 556 described withreference to FIG. 9. The manual mount cell 554 and the accessor mountcell 556 can be replaced with each other. Accordingly, it is possible torealize an upgrade of the library apparatus 2 wherein the drive unit 12has been solely installed by replacing the manual mount cell 554 in thetape drive unit 540 with the accessor mount cell 556. Also, as the driveunit 12 can be of a common structure, except for the manual mount cell554 and the accessor mount cell 556, it is possible to reduce themanufacturing cost of the drive unit 12.

FIG. 10 is the illustration for the explanation of an automaticcartridge-replacement mechanism.

In FIG. 10, the automatic cartridge-replacement mechanism is arrangedwithin the cartridge feeder unit 552. The manual mount cell 554 ismounted to the cartridge feeder unit 552. The mounting members 564 ofthe manual mount cell 554 are fastened to mounting flanges 558a and 558bof the housing 558 of the cartridge feeder unit 552 by screws 578. Thehousing 558 supports a screw rod 582 for generating a conveying forcefor moving a cartridge feeder 580 and a guide rail 584 for guiding thecartridge feeder 580. The screw rod 582 allows the verticalreciprocation of the cartridge feeder 580 along the guide rail 584 bybeing driven to rotate by a motor 586.

The cartridge feeder 580 transports a cartridge 588 from the cell 568 tothe cartridge entry/exit opening of the tape drive unit 550, and fromthe tape drive unit 550 to the cell 568.

Each of the cells 568 in the manual mount cell 554 is defined within thehousing 554a thereof by rack plates 590 sloped at an angle of 5.5°relative to a horizontal plane. Similarly, the cartridge feeder 580 issloped at an angle of 5.5° relative to a horizontal plane.

FIG. 11 is a side view of the manual mount cell 554 for accommodatingthe cartridge.

The manual mount cell 554 is provided with a latch mechanism 592 forpositioning the cartridge 588, a mechanism 594 for preventing themis-insertion of the cartridge 588 and a door 596 rotating upon theentry/exit of the cartridge 588. The latch mechanism 592, themis-insertion preventing mechanism 594 and the door 596 are biasedinward of the cell by means of coil springs not shown.

FIG. 12 is a plan view of the cartridge feeder 580 to be built into thecartridge feeder unit 552, and FIG. 13 is a side view of the cartridgefeeder 580.

The cartridge feeder 580 is provided with endless belts 600a and 600bdriven by a motor. The endless belts 600a and 600b are wrapped aroundpulleys 604a and 604b rotatably held by arms 602a and 602b,respectively. The arm 602a is fixed to a mounting part 608a of a plate606a by screws. The arm 602b is fixed to a mounting part 608a of a plate606b by screws. The plates 606a and 606b are rotatably coupled to eachother by a pin 610.

The pin 610 is provided to penetrate a hole formed at one end of a plate612. Another pin 618 provided on a disk 614 penetrates a hole formed atthe other end of the plate 612. A torque of a motor 616 is transmittedto the disk 614 via gears 620 and 622 fixed to an output shaft of themotor 616. Since a gap between the endless belts 600a and 600b on theside of the manual mount cell 554 is reduced when the disk 614 islocated at a position shown in FIG. 12, the cartridge 588 carried on themanual mount cell 554 is transported to the tape drive unit 550. On theother hand, when the disk 614 rotates by 180° from the position shown inFIG. 12, the plate 612 is pulled leftward to rotate the plates 606a and606b on the pin. Accordingly, since a gap between the endless belts 600aand 600b on the side of the tape drive unit 550 is reduced, thecartridge 558 is transported from the tape drive unit 550 to the manualmount cell 554.

FIGS. 14A and 14B are the illustration for explaining the passage unit13, wherein FIG. 14A is a plan view and FIG. 14B is a side view. FIG. 15is a perspective view of the passage unit 13.

The passage unit 13 is provided with side panels 536a and 536b defininga reference plane for the coupling with the drum unit 10. The sidepanels 536a and 536b are coupled with each other by connecting panels624. Each of the side panels 536a and 536b has positioning pins 626 forpositioning the same when being coupled to the drum unit 10. Fourcasters 630 and four footings 633 are fixed to a bottom panel 628 of thepassage unit 13. On the upper surface of the connecting panels 624, arail carrier 627 for supporting the X rail 20 is fastened by screws 629.The X rail 20 is fixed to the rail carrier 627 by screws 630.

A surface plate 632 to be used as a surface for the coupling with otherpassage units 13 is attached to a front surface and a back surface ofthe passage unit 13, respectively. The surface plate 632 defines areference plane 538. Connectors 634 are arranged in an opening 632a ofeach the front and back surface plates 632, for the connection withsignal cables wired to penetrate the surface plate 632 and theconnecting panel 632.

A power source connector 636 for supplying the electric power to thedrum unit 10 and a connector 638 for transmitting control signals to thedrive unit 10 are withdrawn outside the passage unit 13 through a gapbetween the connecting panels 624.

FIG. 16 is the illustration for explaining the wiring of signal cablesin the passage unit 13 and the drum unit 10.

In the drawing, the passage unit 13 is coupled on the respective sidethereof with the drum unit 10.

The drum unit 10 is provided with an AC power source 640, a power sourcesequence control circuit 642 and a drum control circuit 644. Among theconnectors 634 in the passage unit 13, the connectors 634a and 634bsupply an electric power from the power source provided in the housing 4of the library apparatus 2 to the AC power source 640 via the connector636. A connector 634c transmits a power source control signal from apower source controller provided in the housing 4 of the libraryapparatus 2 to the power source sequence control circuit 642. Aconnector 634d transmits a control signal from a controller forcontrolling the accessor 14 provided in the accessor unit 9 to the drumcontrol circuit 644. A connector 634e transmits a control signal from acontroller for controlling the accessor 14 provided in the accessor unit7 to the drum control circuit 644. The connector 638 connects signalcables connected to the connectors 634c through 634e to the power sourcesequence control circuit 642 and the drum control circuit 644.

FIG. 17 illustrates a coupling state between the drum unit 10 and thepassage unit 13, FIG. 18 is a plan view of the drum unit 10, FIG. 19 isa side sectional view of the drum unit 10, FIG. 20 is the illustrationfor explaining a mechanism for coupling upper and lower units of thedrum unit, FIG. 21 is the illustration for explaining the phasealignment of the coupling mechanism in FIG. 20, and FIG. 22 is theillustration for explaining the connection part of the couplingmechanism in FIG. 20.

The drum units 10A and 10B are coupled, respectively, to both sides ofthe passage unit 13 after the passage unit 13 has been coupled to thereference unit 11. In this regard, since the drum units 10A and 10B havethe same structure, the explanation will be made solely on the drum unit10A and that of the drum unit 10B will be added as necessary.

With reference to FIG. 17, the passage unit 13 is located at a center.On the respective sides of the passage unit 13 are arranged the drumunits 10A and 10B, respectively. In the drum unit 10A, a front endsurface 646a (646b) of a base 654a of a lower unit 652a is brought intocontact with the side panel 536b of the passage unit 13. While, in thedrum unit 10B, a front end surface 656a of a base 654b of a lower unit652b is brought into contact with the side panel 536a of the passageunit 13. The positioning between the passage unit 13 and the drum unit10A is carried out by the insertion of the positioning pin 626 of thepassage unit 13 into a positioning hole 658 of the drum unit 10A.Connectors 660a and 660b provided in the drum unit 10A are coupled tothe connectors 636 and 638, respectively, provided in the passage unit13. The connector 660a is held by the base 654a of the drum unit 10A viaa connector supporting plate 662a.

The positioning and the connector connection between the drum unit 10Band the passage unit 13 are carried out in a similar manner as in thedrum unit 10A. In this regard, connectors in the drum unit 10B are heldon a base 654b of the drum unit 10B via a connector supporting plate662b.

In the lower unit 652a of the drum unit 10A, a plurality of pillars664a, 666a, 668a, 670a, 672a, 674a, 676a and 678a are held on a base654a. The pillars 664a, 666a and 668a are coupled to each other withbeams 670a and 672a. A top panel 655 is provided above the lower unit652a of the drum unit 10A. The drum unit 10A is provided with the drum15 of a heptagonal cross-section as described with reference to FIG. 1.The respective surface thereof has cells arranged in three rows. Withinthe respective cell, the magnetic tape cartridge 588 of Type 13480 isaccommodated. Other than the drum 15, the drum unit 10A is provided withfixed cells 680a. The pillars 668a and 678a support a plurality of cells680 formed from a rightside cell unit and a leftside cell unit as statedlater.

The drum unit 10A is provided with a printed circuit board 682 carryingthe power source 640, the power source sequence control circuit 642 andthe drum control circuit 644. The power source 640 and the printedcircuit board 682 are fixed to the pillar 664a. The power source 640 isconnected to the connector 660a via a power source line 641. The printedcircuit board 682 is connected to the connector 660b via a signal line643.

The upper unit 684a of the drum unit 10A includes pillars 686a, 688a,690a and 692a and a top cover 964a. The drum units 10A and 10B arecoupled to each other with a connecting bar 696a to which are integrallyfixed the pillar 686a of the drum unit 10A and a pillar 692b of the drumunit 10B and a connecting bar 696b to which are integrally fixed thepillar 692a of the drum unit 10A and a pillar 686b of the drum unit 10B.After being coupled by the connecting bars 696a and 696b, a top panel698 is fixed to the connecting bars 696a and 696b with screws.Thereafter, the top cover 964a is fixed to the pillars 686a and 692awith screws.

The drum unit 10B holds the top rail 21 for guiding the vertical column18 of the accessor 14.

The lower unit 652a of the drum unit 10A supports a drum 700 as shown inFIG. 19. Also, the upper unit 684a is provided with an upper drum 702rotatable together with the drum 700.

The base 654a of the lower unit 652a of the drum unit 10A is providedwith four footings 704. The base 654a has a drum motor 50. An outputshaft of the drum motor 50 is coupled to a drum base 706. The drum base706 is of a cup shape. The drum base 706 of a cup shape is coupled tothe drum motor 50 in the upside-down state. Accordingly, the drum base706 is capable of accommodating the drum motor 50 within a height h ofthe drum base 706. This reduced height h contributes to the increase inthe number of cells.

The drum base 706 is provided with a cutout portion 706a. The base 654asupports a lock lever 708 to be rotatable on a shaft 710. When the drumunit 10a is transported, the lock lever 708 is located at a position tobe engageable with the cutout portion 706a. During the use of the drumunit 10A, the engagement between the lock lever 708 and the cutoutportion 706a is released.

Seven flat panels 54 are fastened to a flange 706b of the drum base 706with screws. The flat panel 54 has a flange 54a on a lowermost edgethereof. The flange 54a is fixed to the flange 706b of the drum base 706with screws 712. The flat panel 54 has a flange 54b on one lateral edgethereof. The flange 54b is fastened to another flat panel with screwswhile being overlapped with an end surface of the other flat panel. Aleftside cell unit 240, two central cell units 242a and 242b and arightside cell unit 244 are attached to the flat panel 54-2 to formcells. Positioning pins provided on back surfaces of these cell unitsare inserted into rows of holes 714a, 714b, 714c and 714d. Cartridges52c-1 through 52c-n are accommodated within cells in a middle row ofthree rows supported on the flat panels 54.

The seven flat panels 54 are coupled with the flange 706b of the drumbase 706, respectively, and also fixed to a top panel 716. The drum 700is assembled in such a manner. The assembly is carried out in a factory.

A drum 702 of the upper unit 684a of the drum unit 10A is coupled to thedrum 700 of the lower unit 652a via a coupling mechanism 720. The drum702 includes an top panel 722 and a bottom panel 724. The top panel 722and the bottom panel 724 are coupled with each other with seven flatpanels 726. The drum 702 has a heptagonal cross-section similar to thedrum 700. A leftside cell unit 240, two central cell units 242a and 242band a rightside cell unit 244 are attached to the flat panels 726 toform cells, similar to the drum 700. Cartridges 52c-o through 52c-u areaccommodated within cells in a middle row of three rows of cell.

The drums 700 and 702 are coupled with each other via the couplingmechanism 720 to be rotatable together. As shown in FIG. 20, a stud 728is fixed to the top panel 716 of the drum 700 with screws 730. An endsection 728a of the stud 728 is inserted into a hole 724z of the bottompanel 724 of the drum 702. A bearing 732 is fixed to the top panel 655via a bearing holder 734 with screws 736. The stud 728 is rotatable viathe bearing 732. A connecting arm 738 is secured to the end section 728aof the stud 728 with screws 740. As shown in FIG. 21, the connecting arm738 is provided with three arms 738a. At an end of the respective arm738a, a pin 742 is projected. The pin 742 is inserted into a hole 724aof the bottom panel 724. At an end of the pin 742, a blade spring 744 issecured by a screw 746, as shown in FIG. 20. The blade spring 744operates so that the top panel 724 is prevented from being dismountedfrom the stud 728 due to the vibration caused by, for example, anearthquake. Also as shown in FIGS. 20 and 21, three wheels 748 aresecured to the top panel 655. The wheels 748 support a weight of thedrum 702. Since the weight of the drum 702 is supported by the top panel655, a weight load on the drum motor 50 can be mitigated.

The end section 728a of the stud 728 is inserted into the hole 724z ofthe bottom panel 724. The pin 742 provided at the end of the arm 738a isinserted into a corresponding hole 724a of the bottom panel 724 of thedrum 702. Angles made between every pair of the adjacent arms 738a aredifferent from each other. Accordingly, it is impossible for all of thepins 742 to be inserted into the holes 724a unless the positionalrelationship is correctly adjusted between the pin 742 projected at theend of the arm 738a and the hole 724a of the bottom panel 724.

As shown in FIG. 22, a slide plate 745 is provided in the respectivehole 724a. The slide plate 745 is inserted into a groove 743 provided inthe bottom panel 724, to be movable therein. The slide plate 745 isfixed by a screw 746 after the pin 742 projected from the end of the arm738a has been inserted into the hole 724a. The screw 746 is movablewithin an elongated hole 747.

The drums 700 and 702 are attached after the flat panel 54 of the drum700 and the flat panel 726 of the drum 702 have been positioned to beflush with each other in the same plane while using a jig.

Next, the structure of the drum units 10a and 10b enabling the directentry/exit (DEE) of the cartridge by the operator will be explained. Thedrum units 10a and 10b have a DEE door 64.

FIG. 23 is a top view of the drum unit 10a with DEE door, and FIG. 24 isa side sectional view thereof.

In the drawings, the drum unit 10a has the DEE door 64 rotatable on ahinge 66. A solid line shows a state wherein the door 64 is closed tothe drum unit 10a, while chain line shows a state wherein the door 64 isopen to the drum unit 10a. The door 64 is provided in a DEE window 62formed on a front decorative panel of the drum unit 10a.

A cell drum motor 15a is driven by a motor 50. Seven flat panels arecoupled with the cell drum 15a of a heptagonal cross-section. In FIG.23, two (54-1, 54-2) of the seven flat panels 54 are illustrated. FIG.24 shows two of the seven surfaces of the cell drum 15a of the drum unit10a. Each surface of the cell drum 15a corresponds to one of cellsegments. Each of the flat panels 54-1 and 54-2 has cells arranged at nstages while forming three rows. The respective cell on the flat panel15-1 accommodates cartridges 53L, 53C and 53R. Cells in the cell drum15a are formed by a plurality of combinations of a rightside cell unit244, central cell units 242a and 242b and a leftside cell unit 240 asshown in FIG. 43 stated later, which are then attached to the respectiveflat panels of the cell drum 15a, to be arranged at n stages whileforming three rows. Also, each of the cells in the cell drum 15a isattached to the flat panel at a position sloped upward from a horizontalplane at an angle of 12°. This inclination angle is determined so thatthe cell is prevented from being ejected out of the cell due to thevibration caused by, for example, an earthquake.

During the entry of the cartridge into the cell, the operator opens theDEE door 64 of the drum unit 10a, and inserts the cartridge into therespective cell of the cell drum 15a.

The cartridges 52a and 52b located at upper positions higher than theDEE window 62 to be opened by DEE door 64 are those which have beeninserted through the cartridge entry opening 6 of the cartridge accessstation 5 described with reference to FIG. 1. It is impossible for theoperator to insert the cartridge into a cell located at a positionhigher than the DEE window 62.

Accordingly, the number of stages of cells to which the directentry/exit of cartridge can be carried out by the operator is only m ofn stages.

The cartridges 52a and 52b to be stored in the remaining cells aretransported by the accessor 14 from a position of the cartridge entryopening 6 to the cell on the cell drum 15a of the cell unit 10a.

The drum unit 10a is provided with an upper unit 684a, similar to in thedrum unit 10A or 10B, wherein a drum 702 is coupled with the drum 700.

Each of cartridges 52L, 52C, 52R, 53L, 53C and 53R accommodated in thecells on the cell drum 15a has a bar code label on the front surfacethereof. Also each of the seven flat panels 54 has bar codes 56 in anarea wherein cells are formed opposite to the DEE window 62,corresponding to positions at which the cartridges are to beaccommodated. The bar codes 56 are attached to the flat panels 54 beforethe cell units 240, 242a, 242b and 244 are mounted to the flat panels54. A numbering system of the bar codes 56 attached to the flat panelsof the cell segments 17 of the cell drum 15a is different from that ofthe bar codes given to the cartridges 52L, 52C, 52R, 53L, 53C and 53R.

The bar codes on the cartridges and the flat panels are read by a barcode reader 68. The bar code reader 68 is coupled to a slide guide 76and movable together therewith. The slide guide 76 reciprocates along aslide rail 74. The slide rail 74 is carried on a vertical column base78. The vertical column base 78 carries thereon the bar code reader 68,a lower pulley 72, an upper pulley 106, a pulse motor 70, a positionflag bar 112, the slide rail 74 or others. Around the lower pulley 72and the upper pulley 106, a timing belt 108 is wrapped. A balance weight110 is attached to the timing belt 108 as a counterbalance of the weightof the bar code reader 68. The bar code reader 68 is rotatable on anaxis of the slide guide 76. A motor 82 is provided on the slide guide 76for rotating the bar code reader 68. At a rear end of the bar codereader 68, a sensor flag 84 is provided. A sensor 86 for detecting thesensor flag 84 is provided. The sensor 86 includes a first bar codereader position sensor for detecting that the bar code reader 68 isinclined rightward and a second bar code reader position sensor fordetecting that the bar code reader 68 is inclined leftward.

The pulse motor 70 drives the lower pulley 72. The rotation of the lowerpulley 72 is transmitted to the timing belt 108 which then reciprocatesthe slide guide 76 carrying the bar code reader 68 along the slide rail74. A position of the slide guide 76 on the vertical column base 78 isdetected by counting the number of flags on the position flag bar 112 bya sensor 80 fixed to the slide guide 76. The sensor 80 and the positionflag bar 112 constitute a position detection mechanism for the bar codereader 68.

The vertical column base 78 carries the bar code reader 68 and amechanism for reciprocating the bar code reader 68, which consists ofthe motor 70, the lower pulley 72, the upper pulley 106, the slide guide76, the slide rail 74 and the timing belt 108.

The vertical column base 78, the bar code reader 68, the positiondetection mechanism and the reciprocation mechanism are assembled toform a bar code reader unit 101.

A flange section 78a provided at the lower end of the vertical columnbase 78 is fastened to a base 100 of the drum unit 10a with screws 79.In this regard, the base 100 is provided with footings 102.

Accordingly, the bar code reader unit 101 can be detached from the drumunit 10a by loosening the screws 77 and 79. The flange sections 78a and78b and the screws 77 and 79 are used for mounting/dismounting the barcode reader 101 to/from the drum unit 10a. The base 100 of the drum unit10a has nuts to be engaged with the screws 77. Also, a top panel 104 isprovided with nuts to be engaged with the screws 79. The base 100 andthe top panel 104 have positioning plates or slits for positioning theflange sections 78a and 78b.

A control signal for controlling the bar code reader unit 101 is issuedfrom a control circuit 90 carried on a control printed circuit boardprovided at a corner of the drum unit 10a. The control signal istransmitted to the bar code reader unit 101 from the control circuit 90via a signal cable 94. The bar code reader unit 101 and the signal cable94 are adapted to be connectable to and separable from each other via aconnector not shown. The control circuit 90 transmits a drive signal fordriving the drum motor 50 to the drive motor 50 of the cell drum 15a viaa signal cable 92. If the drum motor 50 and the cell drum 15a constitutethe drum unit, the signal cable 92 is adapted to be connectable to andseparable from the drum motor 50 via a connector not shown.

The bar code reader unit 101 is provided at a rightside front corner ofthe housing of the drum unit 10a. Since the drum unit 10a uses therotating cell drum 15a, it is possible to mount the bar code reader unit101 at the corner of the housing. Access to the upper cells of the celldrum 15a is possible through an opening provided on a back surface ofthe drum unit 10a.

Accordingly, the bar code reader unit 101 can read the bar code labelattached to the inserted cartridge before the cell segment to which theentry/exit operation of the cartridge has been carried out by theoperator reaches a position behind the drum unit 10a.

Such a bar code reader unit 101 can be mounted to the drum unit 10a byscrews at a later stage if necessary as an optional unit. Similarly, adecorative panel provided on the front surface of the drum unit 10a canbe changed from one with the DEE door 64 to one without the DEE door 64.This replacement can be easily carried out by using fastening means suchas screws or the like.

On the other hand, the drum unit 10b shown in FIG. 1 has no DEEfunction, and solely includes the cell drum unit and the controlcircuit. That is, the drum unit 10b corresponds to the drum unit 10A or10B already described with reference to FIGS. 18 through 22.

The drum unit 10b can be converted to a drum unit having the DEEfunction by changing the decorative panel thereof to one having a DEEdoor 64 and mounting the bar code reader unit 101 thereto.

Next, a method will be explained for reading a bar code attached to thecartridge 52 by the bar code reader 68.

FIG. 25 is an illustration for explaining the relationship between ascanning beam of the bar code reader 68 and a cartridge surface on whichthe bar code is attached.

As described with reference to FIG. 23, the cell drum 15a is a rotarydrum of a heptagonal cross-section structured by seven flat panels.Three rows of cells are provided on each of the surfaces of the drum. Ifan end surface of the cartridge 52C in a central row held by cells onthe flat panel 54 is denoted as 52x, on which the bar code label isattached, a locus (C in FIG. 25) of the end surface 52x is inside arotational locus (R in FIG. 25) depicted by a leftside corner of a tipend of the cartridge 52L and a rightside corner of a tip end of thecartridge 52R. A scanning beam of the bar code reader 68 coincides witha vertical directional center of the bar code label on the end surface52x of the cartridge 52C in a central row when the cartridge 52C in thecentral row is correctly positioned in front of the bar code reader 68.Such a scanning beam is represented by 116a in FIG. 25.

However, as shown in FIG. 25, when the cartridge 52R in the rightsiderow is correctly positioned in front of the bar code reader 68, thescanning beam of the bar code reader 68 represented by 116b is inclinedto the center line 116a of the end surface 52x of the cartridge 52R,because the cartridge 52R and the bar code reader 68 are disposed at theinclination angle of 12° relative to the horizontal plane. In thisregard, in the cartridge 52L in the leftside row, the inclination isreverse to that of the cartridge 52R, though it is not illustrated.

It is necessary to correct the scanning beam of the bar code reader inaccordance with positions of rows of cells for accommodating cartridges52.

FIGS. 26 and 27 are illustrations of an inclination adjustment mechanismfor a scanning beam of the bar code reader 68; wherein FIG. 26 is afront view thereof and FIG. 27 is a bottom view thereof.

In FIGS. 26 and 27, the bar code reader 68 is held by a holder 131. Theholder 131 is rotatably held by a shaft 133. The shaft 133 is rotatablymounted to a base 135 which is in turn fixedly secured to the slideguide 76. A shaft 129 having a roller 128 at one end thereof is mountedto the holder 131. The roller 128 is brought into contact with a surfaceof a cam 126 fixedly secured to a shaft 124 rotatably held by the base135. The shaft 129 of the roller 128 is always biased in the arroweddirection P by a spring not shown. This biasing force operates as apressure for forcing the roller 128 to press the surface of cam 126. Theshaft 124 is provided with a pulley 122. The pulley 122 is operativelycoupled to a drive pulley 118 via a belt 120. The drive pulley 118 isfixedly mounted to an output shaft of a motor 82 supported by the base135. An encoder 137 is fixedly secured to the output shaft of the motor82. A slit of the encoder 137 is detected by a motor-stop timing sensor139.

The slit of the encoder 137 is adapted to be capable of detectingpositions at which points (a), (b) and (c) on the surface of the cam 126are in contact with the roller 128. When the point (b) on the surface ofthe cam 126 is in contact with the roller 128, a central position isreached. At point (b), the bar code reader 68 reads the bar code labelon the cartridge 52C in the central row. The scanning beam of the barcode reader 68 represented by 116a. When the point (a) on the surface ofthe cam 126 is in contact with the roller 128, the bar code reader 68reads the bar code label on the cartridge 52R in the rightside row. Thescanning beam of the bar code reader 68 is represented by 116d. When thepoint (c) on the surface of the cam 126 is in contact with the roller128, the bar code reader 68 reads the bar code label on the cartridge52L in the leftside row. The scanning beam of the bar code reader 68 isrepresented by 116c.

FIG. 28 shows a block diagram of a control circuit including a controlportion for the bar code reader (see FIG. 23).

In FIG. 28, the control portion for the bar code reader is provided withCPU 140 consisting of a microcomputer or the like. Also the controlportion for the bar code reader has the following structure.

CPU 140 executes the control operation for the bar code reader 68 orothers in accordance with a program stored in ROM 145. A pulse motordrive circuit 142 drives the pulse motor 70 for reciprocating the barcode reader 68 along the slide rail 74. A Y-axis sensor 80a, whichconstitutes a detection means for detecting a flag 112a of the positionflag bar 112, is mounted to the slide guide 76. An original point sensor80b, which constitutes a detection means for detecting an originalposition flag provided at a lowermost end of the position flag bar 112,is mounted to the slide guide 76. The original point flag can bediscriminated from the position flag 112a because it extends furtherthan the position flag 112a.

A DC motor drive circuit 144 drives a DC motor 82 for rotating the barcode reader 68 on the shaft 133. A motor stop timing sensor 139 consistsof a light emitting element and a light receiving element for detectinga slit provided on an encoder 137 fixedly secured on an output shaft ofthe motor 82. The sensor 130 outputs a stop timing signal in accordancewith the detection of the slit on the encoder 137.

A bar code reader position sensor 86 is provided on a rear portion ofthe bar code reader 68 as shown in FIG. 23. The bar code reader positionsensor 86 consists of a pair of sensors 86a and 86b. The sensor 86a isused for detecting a state wherein the bar code reader 68 rotatesclockwise on the shaft 133 to incline rightward. The sensor 86a isprovided at a position rear left of the bar code reader 68. The sensor86a is provided with a light emitting element and a light receivingelement not shown and outputs a detection signal when a flag 84 on thebar code reader 68 is positioned between the light emitting element andthe light receiving element. The sensor 86b is used for detecting astate wherein the bar code reader 68 rotates counterclockwise on theshaft 133 to incline leftward. The sensor 86b is provided at a positionrear right of the bar code reader 68. The sensor 86a is provided with alight emitting element and a light receiving element not shown andoutput a detection signal when a flag 84 on the bar code reader 68 ispositioned between the light emitting element and the light receivingelement.

Also, the bar code reader control portion executes the communicationwith CPU 150 of a drum control portion via a drum interface circuit 149.

The drum control portion is provided with CPU 150 consisting of amicrocomputer of the like. Also, the drum control portion has thefollowing structure.

CPU 150 executes the control operation for the drum motor 50 or othersin accordance with a program stored in ROM 152. A drum motor drivecircuit 154 drives the drum motor 50 for rotating the cell drum. A drumposition sensor 158 detects a rotational position of the cell drum. Inaccordance with the output from the drum position 158, CPU 150 outputs acontrol signal to the drum motor drive circuit 154 to drive the drummotor 50 so that the cartridges 52c, 52R and 52L in the respective rowson the cell drum shown in FIG. 23 are correctly positioned in front ofthe bar code reader. An interface 156 is used for the communication witha host apparatus.

Next, the bar code label reading operation will be explained.

The bar code reader 68 reads the bar code label as follows.

FIG. 29 is the illustration for explaining the adjustment of a positionat which the reading operation of the bar code reader is carried out.

As stated before, the bar code reader unit 101 is mounted later onto thebase 100 of the drum unit 10a. Also, the cell drum 15a is mounted ontothe base 100 of the drum unit 10a. Because of the dimensional error ofthe bar code reader unit 101 during manufacture and that caused by themounting of the unit 101 to the base 100, there is an offset of relativeposition between the position flag 112a on the position flag bar 112 andthe respective cell in the cell drum 15a.

Accordingly, even though the bar code reader is located at a position infront of a cartridge, for example, the cartridge 52e shown in FIG. 24,in a desired cell, a scanning beam of the bar code reader 68 is actuallyemitted to a position different from the bar code label on the cartridge52e.

Therefore, the bar code reader control portion executes the adjustmentof the position at which the bar code reader 68 reads the bar code priorto the initiation of the actual reading operation of the bar code reader68.

This adjustment of the reading position is as follows:

First, the operator of the library apparatus 2 inputs a command forexecuting the adjustment of the reading position of the bar code reader,through an operator panel on the housing 4. In accordance with thiscommand, a control portion provided on the housing 4 transmits theadjustment command to a control circuit 90 of the drum unit via a signalcable connected to the control circuit 90. The control circuit 90transmits the adjustment command to CPU 150 via an interface 156 of thedrum control portion. CPU 150 transmits the command to CPU 140 via aninterface 149. CPU 140 executes the following steps upon receiving thecommand.

(1) Step S301: As shown in FIG. 29, CPU 140 issues a command to CPU 150of the drum control portion via the drum interface 149 to locate the barcode label of the cartridge in a central row of the cell segment 17 ofthe cell drum 15a at a position correctly in front of the bar codereader 68. CPU 150 drives the drum motor 50 via the drum motor drivecircuit 154 to locate the bar code label of the cartridge in a centralrow of the cell segment 17 of the cell drum 15a at a position correctlyin front of the bar code reader 68. When the drum position sensor 158detects the completion of the positioning operation, CPU 150 informs thecompletion of the positioning operation to CPU 140 via the interface149.

(2) Step S302: Upon the reception of the completion of the positioningoperation signal, CPU 140 determines by the output from the originalpoint sensor 80b whether or not the bar code reader 68 is located at theoriginal point position of the vertical column base 78. If the output ofthe original point sensor 80b is ON, the control proceeds to step S304.

On the contrary, if the output of the original sensor 80b is OFF, thecontrol proceeds to step S303.

(3) Step S303: CPU 140 executes the operation for locating the bar codereader 68 at the original point position. That is, CPU 140 drives thepulse motor 70 via the pulse motor drive circuit 142 to displace the barcode reader downward. If the original sensor 80b is ON, the pulse motor70 is made to stop via the pulse motor drive circuit 142 to locate thebar code reader 68 at the original point position.

(4) Step S304: The operation is executed for emitting the scanning beamof the bar code reader 68 at a position at which the master label 161 isattached. As shown in FIG. 30, the master label 161 is adhered to afront side of a plate member 114 attached to the flat panel 54 of thecell segment 17 of the cell drum 15a. The plate member 114 is providedwith slits 166. The slits 166 are formed on the plate member 114 so thatthe upper ends of the slits 166 are in line with the lower end of themaster label 161. When the bar code reader 68 is located at a positionin front of the master label, CPU 140 first drives the pulse motor 70via the pulse motor drive circuit 142 to displace the bar code reader 68upward. When the number of flags 112a detected by the Y-axis sensor 80areaches a value required for the arrival at the plate member 114, CPU140 interrupts the drive of the pulse motor 70. The number of stages ofthe cells capable of executing DEE is thirty six. Since a position ofthe plate member 114 corresponds to a thirty-seventh stage, the numberof flags to be counted is thirty seven.

(5) Step S306: After the bar code reader 68 has been located at aposition in front of the master label 161, the scanning beam is emittedfrom the bar code reader 68.

(6) Step S308: The operator visually confirms whether or not the lowerend of the scanning beam 164 emitted from the bar code reader 68coincides with the lower end of the master label 161 and with the upperend of the slits 166. If the answer is negative, the control proceeds tostep S310.

(7) Step S310: The operator estimates an amount of offset between thelower end of the scanning beam 116 and the lower end of the master label161 or the upper end of the slits 166, and inputs a value correspondingto this offset amount to CPU 140 via a dip switch (not shown) providedon the bar code reader unit 101. The value to be input by the operatoris the number of pulses of the pulse motor 70, corresponding to theoffset amount. CPU 140 stores this value in an internal register notshown. CPU 140 executes the operation defined by steps S301 through S306when the operator again commands the positional adjustment operation.

(8) CPU 140 executes the following additional operations when step S304is executed. That is, after the position flag 112a corresponding to aposition of the plate member 114 has been detected, CPU 140 confirms thevalue input to the dip switch. If this value is zero, additionaloperations are not carried out. Since the dip switch is set to a valueother than zero as stated above, a number of pulses corresponding to thevalue designated by the dip switch are applied to the pulse motor drivecircuit 142 to drive the pulse motor 70.

(9) According to this application of pulses, the reading position of thebar code reader 68 is adjusted. Then, the operator confirms whether ornot the lower end of the scanning beam 116 emitted from the bar codereader 68 coincides with the lower end of the master label 161 and theupper ends of the slits 166. If the answer is negative, the sameoperation as above is repeated again.

On the other hand, if the operator determines that the coincidence hasbeen obtained, the operator inputs the completion of the positionaladjustment via the operator panel on the housing 4 to CPU 140 via thecontrol circuit, in a similar manner as the initiation of the positionaladjustment. Then, CPU 140 completes the positional adjustment to locatethe bar code reader 68 at the original point.

Accordingly, CPU 140 can execute the positioning operation of the barcode reader with reference to the dip switch as set as described above.

Next, the explanation will be made on the operation for reading the barcode label adhered to the cartridges 52 and 53 inserted into cells ofthe cell drum 15a through the DEE door 64 of the drum unit 10a.

FIG. 31 is a flow chart for illustrating the reading operation of thebar code reader.

First, when a sensor not shown detects that the DEE door of the celldrum 10a is open, CPU 140 commands CPU 150 of the drum control portionto interrupt the rotation of the drum motor 50 and hold the positionthereof. Upon the reception of this command, CPU 150 immediatelyinterrupts the drive of the drum motor 50. Further, CPU 150 determineswhich cell segment in the seven cell segments 17 is positioned in frontof the DEE door 64 in accordance with the output from the drum positionsensor 158. It is assumed that a certain cell segment 17 is located infront of the DEE door 64.

The operator executes the DEE operation (direct entry/exit operation) ofcartridges to cells arranged at n stages while forming three rows. Whenthe DEE operation has been finished, the operator shuts the DEE door.The completion of DEE operation is input through the operator panelprovided on the housing 4 or the drum unit 10a.

When the completion of the DEE operation is input by the operator aftera sensor not shown has detected that the DEE door 64 of the cell drum10a is closed, the bar code reader starts the reading operation shown inFIG. 31.

(1) Step S312: CPU 140 determines whether or not the original pointsensor 80b is ON. If the original point sensor 80b is ON, the controlproceeds to step S316, while if the original sensor 80b is OFF, thecontrol proceeds to step 314.

(2) Step S314: CPU 140 drives the pulse motor 70 to locate the bar codereader at the original point position. When the original sensor 80b isON, CPU 140 interrupts the drive of the pulse motor 70 and the controlproceeds to step S316.

(3) Step S316: CPU 140 commands CPU 150 to locate a cartridge in aselected row in rightside, central and leftside rows of the cellsegments 17 are located in front of the bar code reader 68. For example,CPU 140 designates the rightside rows. CPU 150 of the drum controlportion drives the drum motor 50 so that the cell drum 15a rotates tolocate the cartridge 52R in the rightside row of the cell segment 17 infront of the bar code reader 68.

(4) Step S318: On the other hand, CPU 140 confirms whether or not theinclination of the bar code reader 68 coincides with the designated row.This confirmation is carried out by CPU 140 in accordance with theoutputs from the bar code reader position sensors 86a and 86b. Since CPU140 designates the rightside row at step S316, the outputs from the barcode reader position sensors 86a and 86b must be in such a combinationthat the sensor 86a is ON and the sensor 86b is OFF (while beinginterrupted by the flag 84). If the combination of sensor outputs is NG,the control proceeds to step S320, while if the combination of sensoroutputs is OK, the control proceeds to step S322.

(5) Step S320: CPU 140 executes the inclination operation suitable forthe row designated at step S316. If the central row is designated, theoperation shown in FIG. 33 is executed. If the rightside row isdesignated, the operation shown in FIG. 34 is executed. If the leftsiderow is designated, the operation shown in FIG. 35 is executed. Detailsof these operations will be described later.

(6) Step S322: CPU 140 executes the reading operation of the bar codelabel on all of m stages of cells capable of carrying out the DEEoperation through the DEE door 64. That is, CPU 140 issues a command tothe pulse motor drive circuit 142 to rotate the pulse motor 70. The barcode reader 68 starts to travel upward from the original point position.When the Y-axis sensor 80a detects the first position flag 112a on theposition flag bar 112, CPU 140 interrupts the drive of the pulse motor70. That is, as shown in FIG. 32, during a period wherein the detectionoutput from the Y-axis sensor 80a is "0", drive pulses are applied tothe pulse motor 70 via the pulse motor drive circuit 142. If thedetection output from the Y-axis sensor 80a becomes "1", CPU 140interrupts the issuance of drive pulse after the predetermined number ofdrive pulses have been applied to the pulse motor 70 as a correctionpulse corresponding to the number designated to the dip switch.Accordingly, the bar code reader 68 is located at a position in front ofthe cartridge 52C in the position-corrected state. The application ofcorrection pulses is executed at every stages.

When the positioning operation of the bar code reader 68 has beencompleted, CPU 140 drives the bar code reader to emit the scanning beamand carry out the reading operation of the bar code label. Thepositioning operation and the bar code label reading operation of thebar code reader 68 are repeated a plurality of times corresponding tothe number of cell stages. In this embodiment, these operations arerepeated thirty six times. In this regard, these operations are executedirrespective of whether or not cartridges are stored in the cells. Theresults of the reading operation are stored in RAM 147 by CPU 140, whilebeing classified to the respective cells. CPU 140 prepares, in RAM 147,a table showing the relationship between a cell address representing thecell position and a label number of the bar code label. A cell addressand "all zero" value are given to cells on which the bar code labelcannot be read. Since the bar code label adhered to the flat panel 54 isread by the bar code reader 68 when the cartridge is not stored in thecell, the value represented on the bar code label is stored in RAM 147together with the cell address. The cell address given to the bar codelabel 56b on the flat panel 54 is stored in RAM 147.

(7) Step S324: CPU 140 determines whether or not the cell addresswherein the "all zero" value is stored is present based on the contentof the table stored in RAM 147 for the purpose of confirming thepresence of a non-response stage. If there is no such a cell address,the control proceeds to step S326.

(8) Step S326: CPU 140 locates the bar code reader 68 at a position infront of the master label 161. Then the master label 161 is read by thebar code reader 68 (step S328). When the master label 161 cannot benormally read, CPU 140 determines that the bar code reader has a problemand the control proceeds to step S330. At step 330, CPU 140 interruptsthe operation for reading the bar code label and informs the generationof error via the interface 149 or others to an overall library controlcircuit in the housing 4. The overall library control circuit issues analarm to the operator.

On the other hand, if the master label can be normally read, the controlproceeds to step S332.

(9) CPU 140 confirms whether or not a cartridge is present in a cell. Asstated before, if a cartridge is not stored in a cell, the value of thebar code label read by the bar code reader 68 represents a cell address.Accordingly, if it is confirmed that the cell address coincides with theread value of the bar code label as a result of checking the content ofthe table in RAM 147, it is determined that the cartridge is not presentin the cell. If it is confirmed that there is no cell in which nocartridge is present, it is determined that the bar code label isnormally read by the bar code reader 68 (step S334).

On the contrary, if it is determined that there is a cell in which nocartridge is stored, a flag of the cell address in the table prepared inRAM 147 is ON.

Then CPU 140 drives the pulse motor 70 to locate the bar code reader 68at the original point position (step S338).

(10) Step: S340: CPU 140 transmits the content of the table prepared inRAM 147 to an accessor mechanism controller AMC constituting the libraryoverall control circuit provided in the housing 4 via the drum interface149 and the like.

CPU 140 determines that the treatment of one row of the cells in thesegment 17 has been completed (step 342), and then determines whether ornot the reading of the bar code labels in all the rows is completed(step S344). If any rows to be read are still remain, steps S316 throughS344 are repeated. If the treatment of all the rows has been completed,CPU 140 returns to a waiting state.

Next, the inclination operation executed at step S320 in the flow chartshown in FIG. 31 will be described with reference to FIGS. 33 and 34.

FIG. 33 shows a flow chart of the operation for locating the bar codereader 68 at the reading position in front of the central row ofcartridges.

(1) Step S350: CPU 140 issues a command to CPU 150 of the drum controlportion to designate the central row. CPU 140 determines whether or notthe bar code reader position sensor 86a is ON (step S352). If CPU 140determines that the sensor 86a is ON, CPU 140 drives the DC motor 82 viathe DC motor drive circuit 144 to rotate the cam 126 leftward (FIG. 27)(step S354).

(2) Step S356: The DC motor 82 continues to rotate. If the sensor 86abecomes OFF, CPU 140 confirms whether or not the sensor 86b is ON. Whenthe sensor 86b is OFF, the control proceeds to step S358. While, if thesensor 86b is ON, the control proceeds to step S354 at which the DCmotor 82 is driven to rotate the cam 126 further leftward.

(3) Step S358: After the sensor 86b has become OFF, CPU 140 continues todrive the DC motor 82 until the point (b) on the surface of the cam 126is brought into contact with the roller 128 and the motor stop timingsensor 139 is ON. If the sensor 139 is ON, CPU 140 interrupts the driveof the DC motor 82. Thus the operation has been completed, for locatingthe bar code reader 68 at the reading position in front of the centralrow.

FIG. 34 shows a flow chart of the operation for locating the bar codereader 68 at the reading position in front of the rightside row ofcartridges.

(1) Step S362: CPU 140 issues a command to CPU 150 of the drum controlportion to designate the rightside row. CPU 140 determines whether ornot the bar code reader position sensor 86a is ON (step S364). If thesensor 86a is OFF at step S364, CPU 140 drives the DC motor 82 via theDC motor drive circuit 144 to rotate the cam 126 leftward (FIG. 27)(step S366).

(2) Step S368: If the sensor 86a becomes ON, CPU 140 confirms whether ornot the sensor 86b is ON. When the sensor 86b is OFF, the controlproceeds to step S370. While, if the sensor 86b is ON, the controlproceeds to step S366 at which the DC motor 82 is driven to rotate thecam 126 further leftward.

(3) Step S370: CPU 140 continues to drive the DC motor 82 until thepoint (a) on the surface of the cam 126 is brought into contact with theroller 128 and the motor stop timing sensor 139 is ON. If the sensor 139becomes ON after the sensor 86a has been OFF and the sensor 86b has beenON, CPU 140 interrupts the drive of the DC motor 82 (step S372). Thusthe operation, for locating the bar code reader 68 at the readingposition in front of the rightside row has been completed.

FIG. 35 shows a flow chart of the operation for locating the bar codereader 68 at the reading position in front of the leftside row ofcartridges.

(1) Step S374: CPU 140 issues a command to CPU 150 of the drum controlportion to designate the leftside row. CPU 140 determines whether or notthe sensor 86a is ON (step S376). If the sensor 86a is OFF at step S364,CPU 140 drives the DC motor 82 via the DC motor drive circuit 144 torotate the cam 126 leftward (step S378).

(2) Step S380: If the sensor 86a is OFF, CPU 140 confirms whether or notthe sensor 86b is ON. If the sensor 86b is ON, the control proceeds tostep 382. While, if the sensor 86b is OFF, the control proceeds to step378, at which the DC motor 82 is driven to rotate the cam 126 furtherleftward.

(3) Step S382: CPU 140 continues to drive the DC motor 82 until thepoint (c) on the surface of the cam 126 is brought into contact with theroller 128 and the motor stop timing sensor 139 is ON. If the sensor 139becomes ON after the sensor 86a has been OFF and the sensor 86b has beenON, CPU 140 interrupts the drive of the DC motor 82 (step S383). Thusthe operation has been completed, for locating the bar code reader 68 atthe reading position in front of the leftside row.

As apparent from the above description, it is possible to sequentiallyread the bar code labels on the cartridges stored by the DEE operationby the reciprocation of the bar code reader 68. Since the operation forreading the bar code labels can be completed before the cell segment 17on which the DEE operation has been carried out is positioned in a reararea of the drum unit 10a, it is possible to shorten the transportationtime by the accessor.

FIG. 36 is a side view of a cartridge detection mechanism to be providedin the drum unit 10a or 10b having a DEE door. FIG. 37 is a front viewof a cartridge detection mechanism to be provided in the drum unit 10aor 10b having a DEE door.

In FIG. 36, the cell drum 15a has a plurality of cells 750. The cells750 are arranged at n stages while forming three rows. A photoelectricsensor 752 for detecting whether or not cartridges 588 are present inthe cells 750 and a photoelectric sensor 754 for detecting whether ornot the cartridges 588 are accommodated in the cells 750 in theprojecting-out state.

The photoelectric sensor 752 is constituted by a light-emission element756 attached to the base 100 of the drum unit 10a and a light-receptionelement 758 attached to the top panel 104. The light-emission element756 and the light-reception element 758 are positioned on the base 100and the top panel 104 so that an optical axis between the light-emissionelement 756 and the light-reception element 758 is interrupted by acartridge 588S normally accommodated in the cell 750.

The photoelectric sensor 754 is constituted by a light-emission element760 attached to the base 100 of the drum unit 10a and a light-receptionelement 762 attached to the top panel 104. As shown in FIG. 36, thelight-emission element 760 and the light-reception element 762 arepositioned on the base 100 and the top panel 104 so that an optical axisbetween the light-emission element 760 and the light-reception element762 is not interrupted by a cartridge 588S normally accommodated in thecell 750 but is interrupted by a cartridge 588T accommodated in the cell750 in the projecting-out state.

The photoelectric sensors 752 and 754 have three pairs of thelight-emission element and the light-reception element, respectively.Three light-emission elements 760L and 760C and 760R are attached to thebase 100 via a mounting member 764. Three light-reception elements 762L,762C and 762R are attached to the top panel 104 via mounting member 766.

FIG. 38 is the illustration for explaining a mechanism for cleaning thecartridge detection mechanism. FIG. 39 is a perspective view of part ofthe cleaning mechanism shown in FIG. 38.

In FIG. 38, the light-emission elements 756L, 756C and 756R in thephotoelectric sensor 752 and the light-emission elements 760L, 760C and760R in the photoelectric sensor 754 are secured onto the mountingmember 764. Three levers 768a, 768b and 768c are rotatably held on themounting member 764, respectively, via pins 770. Each of the levers 768athrough 768c carries brushes 772 and 774, the levers 768a through 768care coupled with each other by a connecting bar 776, respectively, bypins 778. In relation to the connecting bar 776, the lever 768a isrotatable at one end of the connecting bar 776, the lever 768b isrotatable at a center thereof and the lever 768c is rotatable at theother end thereof. The lever 768b is biased in the arrowed direction Aby a spring 780. One end of the spring 780 is hooked to a hole 782 ofthe lever 768b and the other end to an upright piece 764a cut and bentfrom the mounting member 764. The movement of the lever 768a is limitedby an upright piece 764b cut and bent from the mounting member 764.

A contact plate 786 is attached to the lever 768b to be rotatable on ashaft 784. The contact plate 786 is provided at a position to be broughtinto contact with a roller 790 rotatably mounted to a tip end of a levermember 788 attached to the flange 706b of the drum base 706 of the drumunit 10a. When the roller 790 moves in the arrowed direction B as thedrum 15a rotates, the roller 790 causes the contact plate 786 to rotatein the arrowed direction C. The lever 768b rotates on the pin 770together with the contact plate 786. According to the rotation of thelever 768b, the brushes 772 and 774 provided on the respective levers768a through 768c slide on the surfaces of the light-emission elements756L, 756C, 756R, 760L, 760C and 760R. Accordingly, the surfaces of thelight-emission elements 756L, 756C, 756R, 760L, 760C and 760R are alwayscleaned when the drum 15a rotates.

In this regard, when the drum 15a rotates reverse to the alloweddirection B, the contact member 786 rotates on the shaft 784, but thelever 768b is still maintained at a position shown by a solid line inFIG. 38 by the action of the upright piece 764a. When the engagementbetween the contact member 786 and the roller 790 is released, thecontact member 786 returns to a position shown in FIG. 38 by a biasingforce of a spring 792.

FIG. 40 is the illustration for explaining the structure of a drum unitwherein a DEE magazine is used.

In FIG. 40, a drum unit 169 includes an upper unit 176 and a lower unit171. In the lower unit 176, a magazine drum 175 is rotatably providedbetween a base 170 supported by footing 172 and a top panel 174. Theupper unit 176 is provided with a cell unit rotatable with the magazinedrum 175.

The magazine drum 175 is provided with a flange 178. The magazine drum175 is driven to rotate when the flange 175 is rotated by a drum motor173. The magazine drum 175 has a heptagonal cross-section similar to thecell drum 15a described with reference to FIGS. 23 and 24. The magazinedrum 175 is constituted by seven flat panels assembled to have aheptagonal cross-section. Since FIG. 40 is a front view of the drum unit169, only one surface of the magazine drum 175 is illustrated.

Frame panels 180 and 182 are attached to the respective flat panel ofthe magazine drum 175. Four magazine shelves 184a through 184d areformed between the frame panels 180 and 182 in a stacked manner. Each ofthe magazine shelves 184a through 184d has guide plates 186, 187, 188and 189 used for an entry guide for the magazine. Position correctionmarks 190 and 192 are provided on the guide plates 186 and 188,respectively.

On the front surface of the drum unit 169, a decorative panel with theDEE door 64 is attached in a manner similar to that of the drum unit 10ashown in FIG. 23. A magazine 200 is loaded into each of the magazineshelves 184a through 184d by the operator while the DEE door 64 isopened.

FIG. 41 is an illustration for explaining the operation for loading themagazine to the magazine shelf of the drum unit.

With reference to FIGS. 41, 42A and 42B, the magazine 200 is providedwith cells arranged at six stages while forming three rows. Accordingly,it is possible to load eighteen cartridges 202 at once in the drum unit169 by the magazine 200. The magazine 200 has a grip 204 on the uppersurface thereof and positioning holes 201a and 201b on the back surfacethereof.

The magazine 200 is loaded into the magazine shelf 184a formed on theframe panels 180 and 182 along the guide plates 186, 187, 188 and 189.These guide plates 186 through 189 are accurately attached to the framepanels 180 and 182 so that a predetermined relationship is obtainedbetween a lateral directional (X-directional) position thereof and apositioning reference point 169a of the drum unit 169 (see FIG. 40).

The magazine 200 is placed on magazine-placing plates 206 and 208provided on a shelf plate 218 of the magazine shelf 184a. As shown in31A, a space 220 is provided between the rear edge of the plates 206 and208 and a back panel 216. When the magazine 200 is loaded, guideprojections 220b provided on the lower part of the magazine 200 areengaged with guide grooves 206a and 208a formed on the plates 206 and208, respectively. The magazine 200 is inserted along the guide grooves206a and 208a. When the magazine 200 has been fully inserted to theinnermost area of the magazine shelf 184a, the engagement between theguide projections 220b provided on the lower part of the magazine 200and the guide grooves 206a and 208a is released, and the guideprojections 220b is located within the space 220, as shown in FIG. 42B.

In other words, the positioning holes 201a and 201b are engaged withprojections 212 and 210, respectively, provided on the back panel 216constituting the magazine drum 175. These projections 210 and 212 areattached to the back panel 216 so that a predetermined relationship isobtained between the height directional (Y-directional) positions ofrecessed portions 210a and 212a of these projections 210 and 212 and thepositioning reference point 169a defined at a rightside lower end of thedrum unit 169 shown in FIG. 40.

Moreover, the inward directional positioning of the magazine 200 isachieved by abutting the back surface of the magazine to positioningprojections 214 provided on the back panel 216 of the magazine drum 175.These projections 214 are attached to the back panel 216 so that apredetermined relationship is obtained between the inward directional(Z-directional) positions of the projections 214 and the positioningreference point 169a defined at a rightside lower end of the drum unit169 shown in FIG. 40.

As stated above, the magazine 200 is accurately located at thepredetermined position in the magazine shelf 184 of the magazine drum175. In this regard, the position of the magazine shelf 184a for themagazine 200 is one wherein a rotating path of the cartridge 202accommodated in the cell of the magazine 200 is the same as that of thecartridge 52 or 53 accommodated in the cell of the drum unit 10a shownin FIG. 23. That is, the respective cell in the magazine 200 is formedwhile using the positioning holes 201a and 201b as a reference.

Accordingly, after the magazine drum 175 has been driven to rotate bythe drum motor 173 to a position opposite the accessor 14, thecartridges 202a and 202b in the cells of the magazine 200 can be grippedby the accessor 14 similar to the cartridges 52 and 53 stored in thecells of the drum unit 10a.

FIG. 43A is a plan view for illustrating the detailed structure of themagazine, FIG. 43B is a front view thereof, and FIG. 43C is a back viewthereof.

With reference to FIGS. 43A through 43C, the magazine 200 has a housing203 made of metal and a grip 204 on the upper part thereof for carryingthe magazine. Other grips 222 and 232 are provided in upper and lowerareas of the front surface of the housing 203 for loading the magazine200 onto the magazine shelf 184a, the grips 222 and 232 are fixed to thehousing 203 via plates 224 and 234 made of metal such as stainlesssteel. The housing 203 has an opening 226 for gripping the grip 222. Thehousing 203 is provided with holes 228 for allowing a light from aphotoelectric sensor for detecting the presence of the cartridge to passtherethrough. The hole 228 for detecting the presence of the cartridgein the central row is not provided because the opening 226 for grippingthe grip is formed in the housing 203. The surface of the metallic plate224 is used as a position 230 for detecting the presence of themagazine.

The magazine 200 has cells 254 for accommodating the cartridges,arranged at six stages while forming three rows. These cells 254 aredefined by a leftside rack 240, two intermediate racks 242a and 242b anda rightside rack 244. These racks 240, 242a, 242b and 244 are fastenedto a metallic panel 203a located at a position different from that of aback panel 203c of the housing 203.

The leftside rack 240 is fastened to the metallic panel 203a with screws246. The intermediate rack 242a is fastened to the metallic panel 203awith screws 248. The intermediate rack 242b is fastened to the metallicpanel 203a with screws 250. The rightside rack 244 is fastened to themetallic panel 203a with screws 252.

A plurality of bar code labels 256 are attached to the metallic panel203a. These bar code labels 256 correspond to the respective cells 254.

Thereby, according to the magazine 200 having these bar code labels, theoperation for detecting the presence of the cartridge is assuredlycarried out even when the bar code reader unit 101 such as one describedwith reference to FIGS. 23 and 24 is mounted to the drum unit 169.

Also, it is possible to load a number of cartridges at once into thelibrary apparatus 2 by using the magazine 200. Since it is possible tohandle the drum unit 169 using the DEE magazine 200 in a manner similarto drum units of other types, after the DEE magazine has been loadedinto the magazine shelf 184, it is not always necessary to transfer thecartridges 202 in the DEE magazine loaded to the magazine shelf 184 tocells in another drum unit. Also, after the loading of cartridge intothe cells in the other drum unit has been completed, the drum unithaving the magazine shelf 184 in which the DEE magazine 200 is loadedcan be handled in a manner similar to the other drum unit, resulting inthe increase in the number of cartridges to be accommodated therein.

The drum unit 169 may be installed in place of the drum unit 10b of thelibrary apparatus 2 shown in FIG. 1. Also, the library apparatus 2 shownin FIG. 1 may include four drum units 10b shown in FIG. 1, each solelyprovided with a cell drum 15b, one drum unit 10a shown in FIG. 23, andone drum unit 169. There are many possibilities for extending the drumunits as shown in FIG. 2.

FIGS. 44, 45 and 46 are illustrations for explaining the leftside rack240, the intermediate rack 242 and the rightside rack 244, respectively.

In FIG. 44, the leftside rack 240 is molded in ABS resin. The leftsiderack 240 is provided with shelf plates 241 for defining cells 254. Eachof the shelf plates 241 extends obliquely upward from a back plate 243.An inclination angle of the shelf plate 241 relative to a horizontalplane is 12°. In other words, the inclination angle of the shelf plate241 relative to the back plate 243 is 78°. The shelf plate 241 has astepped portion 243a to be engageable with a projection 584S formed onthe bottom surface of the magnetic tape cartridge 588 of a type 13480shown in FIG. 47. The inclination angle of the shelf plate 241 and thestepped portion 243a constitute an anti-drop mechanism for the cartridge588.

The back plate 243 has projections 245a, 245b and 245c on the surfaceopposite to the surface on which the shelf plate 241 is formed. Theprojection 245a is inserted into a hole 714a-1 in a row of holes 714ashown in FIG. 19. The projections 245b and 245c are inserted into holes714a-2 and 714a-3, respectively. In this manner, when the threeprojections 245a through 245c of the back plate 243 are inserted intothe holes 714a-1 through 714a-3, respectively, and fastened to the flatpanel 54 by screws not shown, a camber thereof formed during the moldingcan be corrected. In this regard, positions on the leftside rack 240 atwhich screw holes are provided are shown in FIG. 43.

In FIG. 45, the intermediate rack 242a is molded in ABS resin in asimilar manner as the leftside rack 240. Since the intermediate rack242b has the same structure as the intermediate rack 242a, theexplanation thereof will be omitted. The intermediate rack 242a isprovided with shelf plates 247 for defining cells 254. Each of the shelfplates 247 extends obliquely upward from a back plate 249. Aninclination angle of the shelf plate 247 relative to a horizontal planeis 12°. In other words, the inclination angle of the shelf plate 247relative to the back plate 249 is 78°. The shelf plate 247 has a steppedportion 251 to be engageable with a projection 584T formed on the bottomsurface of the magnetic tape cartridge 588 of a type 13480 shown in FIG.47. The inclination angle of the shelf plate 247 and the stepped portion251 constitute an anti-drop mechanism for the cartridge 588.

The back plate 249 has projections 253a, 253b and 253c on the surfaceopposite to the surface on which the shelf plate 247 is formed. Theprojections 253a through 253c are inserted into holes 714b-1 through714b-3 of the flat panel 54, respectively, shown in FIG. 19. In such amanner, when the three projections 253a through 253c of the back plate243 are inserted into the holes 714b-1 through 714b-3, respectively, andfastened to the flat panel 54 by screws not shown, a camber thereofformed during the molding can be corrected. In this regard, thepositions on the intermediate rack 242 at which the screw holes areprovided are shown in FIG. 43.

In FIG. 46, the rightside rack 244 is molded in ABS resin. The rightsiderack 244 is provided with shelf plates 255 for defining cells 254 inassociation with the intermediate rack 242b. Each of the shelf plates255 extends obliquely upward from a back plate 257. An inclination angleof the shelf plate 247 relative to a horizontal plane is 12°. In otherwords, the inclination angle of the shelf plate 255 relative to the backplate 257 is 78°. The shelf plate 255 has a stepped portion 256 to beengageable with a projection 584T formed on the bottom surface of themagnetic tape cartridge 588 of a type 13480 shown in FIG. 47. Theinclination angle of the shelf plate 255 and the stepped portion 256constitute an anti-drop mechanism for the cartridge 588.

The back plate 257 has projections 261a, 261b and 261c on the surfaceopposite to the surface on which the shelf plate 255 is formed. Theprojections 261a through 261c are inserted into holes 714d-1 through714d-3 of the flat panel 54, respectively, shown in FIG. 19. In such amanner, when the three projections 261a through 261c of the back plate257 are inserted into the holes 714c-1 through 714c-3, respectively, andfastened to the flat panel 54 by screws not shown, a camber thereofformed during the molding can be corrected. In this regard, thepositions on the rightside rack 244 at which screw holes are providedare shown in FIG. 43.

In such a manner, the combination of the leftside rack 240, the twointermediate racks 242a, 242b and the rightside rack 244 enables todefine the cells arranged at three stages while forming three rows.

In this regard, a plurality of sets of the leftside rack 240, the twointermediate racks 242a, 242b and the rightside rack 244 are attached tothe flat panel 54 while being arranged in the height direction of theflat panel 54 in a stacked manner. Between one set of the leftside rack240, the two intermediate racks 242a and 242b and the rightside rack 244and another set directly above the same, additional cells are definedfor accommodating the cartridges. Since the DEE magazine 200 shown inFIG. 43 cannot form cells in the uppermost portion thereof because ofthe provision of grip 222, cells arranged at six stages while formingthree rows are defined.

Also, by the combination of the leftside rack 240 and the rightside rack244, cells arranged at six stages while forming one row can be defined.This is a case when a fixed cell 680a is defined in a pillar 668a of thedrum unit 10A.

Alternatively, the combination of the leftside rack 240, the rightsiderack 244 and the single intermediate rack 242a can define cells arrangedat six stages while forming two rows.

As described above, it is possible to obtain various cell combinationsin accordance with the number of the intermediate racks 242a and 242barranged between the leftside rack 240 and the rightside rack 244.Further, such combinations of the leftside rack, the rightside rack andthe intermediate rack can be used for defining cells for the DEEmagazine.

Accordingly, when the cells for the DEE magazine, the fixed cell and thedrum unit are defined, the leftside rack, the central cell, and therightside rack can be commonly used. This enables the mass production ofparts and a reduction in the manufacturing cost of cells.

FIGS. 48 through 57 are the illustration for explaining methods forcoupling the respective units in the library apparatus according to thepresent invention.

FIG. 48 is the illustration for explaining a method for manufacturingthe library apparatus shown in FIG. 2.

(a) Installation of Reference Cell Unit

In FIG. 48, a thread 800 is straightly extended on the floor in atensioned state between poles 802a and 802b, while a position at whichthe reference unit 11 is to be installed is located at a center thereof.In this regard, when the thread 800 is extended on the floor in FIG. 48,the respective units are not located at a position at which the libraryapparatus is to be installed, but temporarily stored in part of a roomin which the library apparatus is to be installed. Accordingly, thearrangement of the respective units shown in FIG. 48 is imaginary.

The poles 802a and 802b supporting the thread 800 are provided so that aheight L thereof from the floor surface is, for example, 60 mm.

Next, marks 804a through 804f are marked on the floor surface atpositions at which the respective units are to be installed. There aresix marked positions on the floor. Heights L1 through L6 of the thread800 from the floor surface are all measured at the marked positions. Themarked position 804d at which the reference unit 11 is to be installedis selected as a reference point. A correction value is calculated fromthese measured values. The calculation is carried out by the followingequation: Correction Value=L-(Minimum Value in L1 through L6). Acorrected height of the reference unit 11 at the mark 804d is calculatedby the following equation: Corrected Height=L3+Correction Value.

The reference unit 11 which is a reference locker is actually installedso that the corrected height is equal to the calculated value at themarked position 804d. The marked position 804d is defined at one cornerof the reference unit 11 at which the footing shown in FIG. 49A isprovided. This marked position 804d becomes the reference point 11a.

After the reference point 11a of the reference unit 11 coincides withthe mark 804d, the heights of the footings B through D are adjustedwhile fixing the footing A. The adjustment of the heights of thefootings B through D is carried out by using a level 808 placed on the Xrail 20 and a vertical measurement tool including a thread 810 hangingdown from a member 808 on the reference unit 11 and a weight 812.

(b) Coupling of Passage Unit to Reference Cell unit

The reference unit 11 has a structure similar to the passage unit 13wherein signal cables and connectors are built-in for transmittingelectric power, a power source sequence control signal and a drumcontrol signal. First, the connectors of the reference unit 11 arecoupled with those of the passage units 13 as shown in FIG. 50.

Thereafter, the passage units 13 are joined to both sides of thereference unit 11 while using the reference unit 11 as a reference.Footings A and C of the passage unit 13 are adjusted in height directionso that the upper edges of the side panels 536a, 536b of the passageunit 13 is flush with the upper edge of the surface plate 538 of thereference unit 13. Then, the footings C and D are adjusted in height sothat a level not shown placed on the X rail 20 is within a tolerance.Further, the footings B and D are adjusted in height.

Next, a jig 822 is placed on a rail support 627 provided in the passageunit 13 and the upper surface of the side panel 536b in a bridge manner.The jig 822 is preliminarily prepared so that the upper surface thereofbecomes horizontal when the upper end surfaces of a rail support 627provided in the passage unit 13 and of the side panel 536b arehorizontal. The footings B, C and D are adjusted in height so that alevel placed on the jig 822 is within a tolerance, while fixing theheight of the footing A.

After the X rail 20 of the passage unit 13 has been joined to a railsupport for the X rail provided in the reference unit 11, the X rail 20is fastened to the rail support with screws. The structure of the railsupport 627a in the reference unit 11 is the same as the rail support627 of the passage unit 13. To the rail support 627a of the referenceunit 11, the X rail 20 is fastened with screws 814 and also the other Xrail 20 is fastened with screws 816. To the rail support 627, the X rail20 is fastened with screws 818. To the rail support 627 of the passageunit 13b, the X rail 20 is fastened with screws 820.

The height adjustment between the reference unit 11 and the passage unit13 is carried out while using the side panel 536a of the passage unit13. However, this is not limited thereto. For example, the heightadjustment may be carried out so that the upper surfaces of the railsupports are flush with each other. Alternatively, the height adjustmentmay be carried out so that the upper surfaces of the rack supports towhich a pinion of the X motor 42 is coupled are flush with each other.

Further passage units 13 corresponding to the number of drum units to becoupled with the library apparatus 2 can be coupled by repeating theoperation described before. Since eight drum units are coupled in thelibrary apparatus shown in FIGS. 2 and 487, two passage units 13 arearranged on each of both sides of the reference unit 11.

(c) Coupling of Accessor unit to Passage Unit

As shown in FIG. 51, the accessor unit 9 is arranged adjacent thepassage unit 13. The heights of the footings A and C of the accessorunit 9 are adjusted so that the upper surface of a rail support 627b ofthe accessor unit 9 and the rail support 627 of the passage unit 13 areflush with each other. The heights of footings C and D are adjustedwhile placing a level on the X rail 20 so that the level is within atolerance. Then, while observing a vertical measurement tool consistingof a thread attached to the pillar 35a of the accessor unit 9 (see FIG.6) and a weight, the heights of footings B, C and D are adjusted so thatthe height is within a tolerance while the footing A is maintained in afixed state.

After the height adjustment of the footings A through D has beencompleted, an X rail 20d is shifted. Then the X rail 20d is fastened tothe rail support 627 with screws 832. Further, the X rail 20d isfastened to the rail support 627b of the accessor unit 9 with screws830. Next, an X rail 20e of half a length is fastened to the railsupport 627b with screws 834. In this regard, the X rail 20 has beenalready fastened to the passage unit 13 with screws 836.

The coupling of the accessor unit 7 to the passage unit 13 is carriedout in the same manner as described above.

(d) Coupling of Drum Unit to Passage Unit

The drum units 10A and 10B described with reference to FIG. 17 aretransported from a factory to an installation site in a state whereinthe lower unit 652a is separated from the upper unit 684a. The assemblyof the lower unit 652a and the upper unit 684a is carried out in a roomwherein the library apparatus 2 is to be installed. In the couplingoperation, the end section 728a of the stud 728 provided in the upperpart of the drum 700 in the lower unit 652a is inserted into the hole724z of the bottom panel 724 of the drum 702 in the upper unit 684a, andthe pin 742 in the end portion of the arm 738a of the connecting arm 738fixed to the stud 728 is inserted into the hole 724a.

Thereafter, the drum units 10A and 10B are arranged adjacent the sidepanels 536a and 536b of the passage unit 13. Then, the referencesurfaces 646a and 646b on the front surface of the drum units 10A and10B are joined to the side panels 536a and 536b. Further, the height ofthe upper edges of the reference surfaces 646a and 646b are adjusted tobe equal to that of the upper ends of the side panels 536a and 536b.This height adjustment is carried out via footings A and C. The drumunits 10A and 10B are fastened to the passage unit 13 with bolts 840a,840b, 842a and 842b. The inclination in the front/rearward directions iscorrected via footings B and D while using a height measurement toolconsisting of a thread hanging down from the top panel 655a of the drumunit 10A and 10B and a weight. Then, the inclination in the lateraldirection is corrected via footings C and D or A and B. After thecompletion of the adjustment, the drum units 10A and 10B are fastened tothe passage unit 13 with bolts 840a through 840d and 842a through 840d.

The drum unit 10A and 10B are coupled to the passage unit 13 one by one.

(e) Coupling of Drum Unit to Upper Unit

As shown in FIG. 53, after the drum units 10A and 10B have been coupledto each other by the connecting bars 696a and 696b, the top panel 698 isfixed by screws. Further, the cover 694 is fastened to the pillars 688aand 690a with screws 844.

(f) Mounting of Upper Rail

As shown in FIG. 54, the upper rail 21 is attached to the accessor unit9 and then sequentially to the respective units.

(g) Coupling of Drive Unit

Then, as described with reference to FIGS. 8 and 9, the manual mountcell 554 of the tape drive unit 540 in the drive unit 12 is replaced bythe accessor mount cell 556. The drive unit 12 is fastened to thereference unit 11 with screws 546.

(h) Finally, as described with reference to FIGS. 14 through 18, theconnectors 636 and 638 in the passage unit 13 are connected to theconnectors 660a and 660b in the drum unit 10.

In the above-mentioned manner, the library apparatus 2 is assembled.

Since the library apparatus 2 is assembled by units, the time necessaryfor the assembly can be shortened, after parts of the apparatus havebeen taken to the installation site. Also, since the parts are conveyedas units, it is easy to take the same into a room wherein the libraryapparatus is to be installed, even if the library apparatus is capableof accommodating a large number of cartridges therein.

In addition, since the upper unit can be coupled, it is possible toincrease the number of cartridges to be accommodated in the heightdirection.

Since it is possible to selectively arrange the drum units or othershaving DEE magazines, the degree of freedom for systematizing thelibrary apparatus 2 can be increased to a great extent.

FIG. 55 illustrates one embodiment of a hardware of the libraryapparatus 2. In FIG. 55, four host computers 301 through 304 areconnected to the library apparatus 2 via channel interface buses 311through 314, respectively.

As such channel interface buses 311 through 314, a block multiplexerchannel interface, an SCSI interface or the like can be used. Forexample, four directors 321 through 324 are provided in the libraryapparatus 2. The directors 321 and 323 have channels A, B, C and D,respectively. The directors 322 and 324 have channels E, F, G and H,respectively.

The channel interface bus 311 from the host computer 301 is connected tothe channels A of the directors 321 and 323, and the channel interfacebus 312 from the host computer 302 is connected to the channels Bthereof. Also, the channel interface bus 313 from the host computer 303is connected to the channels E of the directors 322 and 324, and thechannel interface bus 314 from the host computer 304 is connected to thechannels F thereof. Note the channels C and D of the directors 321 and323 and the channels G and H of the directors 322 and 324 are not used.

Two channels a and b are provided on a terminal unit side of each ofdirectors 321 through 324, wherein the channel a is for arecording/regeneration device and the channel b is for the accessorcontrol. The directors 321 and 322 commonly have eightrecording/regeneration devices 340 commonly connected to each other viadevice buses 331 and 332 from the channel a. Accordingly, the directors321 and 322 can have access to the recording/regeneration device 340 viathe channel a to carry out the writing/reading operation thereto. Theseeight recording/regeneration devices 340 are provided in the drive units12a and 12c.

The directors 323 and 324 have eight recording/regeneration devices 350commonly connected to each other via device buses 333 and 334 from thechannel a. Accordingly, the directors 321 and 322 can have access to therecording/regeneration device 350 via the channel a to carry out thewriting/reading operation thereto. These eight recording/regenerationdevices 350 are provided in the drive units 12b and 12d.

A device interface bus 238-1 connected to the channels b of thedirectors 321 and 322 is connected to the channel a of an accessorcontroller 228. Similarly, a device interface bus 338 extending from thechannels b of the directors 323 and 324 is connected to the channels bof the accessor controller 328.

An accessor controller 330 is a spare wherein a device interface bus 338connected to the channels b of the directors 321 and 322 is connected tothe channel a thereof, while a device interface bus 339 connected to thechannels b of the directors 323 and 324 is connected to the channel bthereof.

The accessor controllers 328 and 330 carry out the operation upon thereception of a command from any one of the directors 321 through 324.Machine controllers 351 and 352 are provided, under the supervision ofthe accessor controller 328, for controlling the accessor 14 in theaccessor unit 7 and the accessor 14 in the accessor unit 9,respectively. In addition, drum controllers 361 and 362 are provided,under the supervision of the accessor controller 328, for controllingthe cell drums 15a and 15b in the respective drum units 10a, 169 orothers. In this regard, for the simplicity of the explanation, two celldrums 15a and 15b are shown as cell drums in FIG. 55.

The machine controllers 351 and 352 and the drum controllers 361 and 362are also commonly connected to the accessor controller 330.

Each of the host computers 301 through 304 designates a logical machinenumber address, based on the demand for the input/output device to thelibrary apparatus 2 accompanied with the job execution, and issues amove command functioning as an input/output starting command to thedirectors 321 and 322 through the channel allocated thereto. If thenormal reception answer to the move command is obtained from thedirector side, the host computer transfers a data byte (commandparameter) thereto as a medium-transportation information.

This data byte includes an address from which the cartridge exits(original address) and an address which the cartridge is delivered(delivery address), and is stored in a queuing table of the accessorcontroller 328. When it has recognized that the accessor 14 of theaccessor units 7 and 9 is empty, the accessor controller 328 takes outthe original address and delivery address from the queuing table, andmakes the machine controllers 351 and 352 move the accessor 14. Also, ifnecessary, the accessor controller makes the drum controllers 361 and362 rotate the cell drums 15a and 15b.

In this case, the accessor controller 328 converts the original anddelivery cell addresses taken out from the queuing table to a rotatingangle θ of the cell drum and a position of the accessor on the X, Ycoordinates while referring to a conversion table. The cell drum and theaccessor are driven accordingly.

FIG. 56 is the illustration of one embodiment of a hardware structure ofthe accessor controller 328.

In FIG. 56, CPU 270 is connected via a bus 275 to ROM 276, DRAM 278, anhigher interface control portion 284, a machine controller interfacecontrol portion 288, a drum interface control portion 292 and deviceinterface control portion 294 and 2102. CPU 270 carries out the controloperation based on a program stored in ROM 276. DRAM 278 has a queuingtable 280 and a cell address conversion table 283. The queuing table 280stores a move command issued from the host computer via the director.The cell address conversion table 282 stores a drum rotation angle θ anda coordinate (X, Y) of a position to which the accessor is deliveredwhile using the cell address as an entry.

Also, a CE panel 296 having a display 298 and a floppy disk selectionswitch 2100 and a floppy disk device 2104 are connected to CPU 270 viathe interface control portions 294 and 2102.

FIG. 57 is the illustration of one embodiment of a hardware structure ofthe machine controller 351.

In FIG. 57, CPU 400 is connected via a common bus 401 to RAM 416 havinga program storage area 424 and a work area 426, and a non-volatilememory 420. RAM 416 is commonly connected via a bus switching circuit418 to the accessor controller 328. An operation control program isinstalled into the program storage area 424 from the floppy disk device2104 of the accessor controller 328 via the bus switching circuit 418.The accessor controller 328 is connected to the machine controller via asignal line to transmit a bus switching signal to the bus switchingcircuit 418 and for transmitting data and addresses thereto.

CPU 400 is connected via an interface 422 to an interface 156 of thedrum control portion. CPU 400 transmits information via these interfaces422 and 156 to CPU 150. The interface 422 is also connected to a port288A of the machine controller interface control portion 288 in theaccessor controller 328.

A detection output is input to CPU 400 from the reflection typephotoelectric sensor 162 provided at a tip end of the hand assembly 16.The drivers 402, 406 and 414 for driving the X-axis motor 42, the Y-axismotor 46 and the θ-rotation motor 25 of the accessor 14 are connected toCPU 400. CPU 400 is also connected to a counter 410 for counting outputsfrom an encoder 409 attached to the X-axis motor 42, a counter 412 forcounting outputs from an encoder 409 attached to the Y-axis motor 46 anda counter 413 for counting outputs from an encoder 409 attached to theθ-rotation motor 25, to be able to read the counted numbers thereof andto reset them.

Next, the operation for correcting a position of the accessor 14 used asa carriage will be described.

FIGS. 58A and 58B are illustrations for explaining the sensors providedin the accessor 14.

In FIG. 58A, there are illustrated a sensor 162 mounted on the handassembly 16 and a sensor 163 mounted on the rail base 32, for detectinga position in the X-direction. In FIG. 58B, a sensor 167 is illustratedfor detecting a position of the base 27 of the hand assembly 16 relativeto the base 24 of the hand assembly.

The X-directional positioning of the accessor 14 is carried out whileusing a position flag 165 representing an original point and provided inthe accessor unit 9, as a reference. The original position flag 165 isdetected by the sensor 163. However, there may be a case wherein anactual distance in the assembly is different from a predetermined value,between a position at which the sensor 163 is attached on the rail base32 and a center of grip of a hand of the hand assembly 16. In such acase, even if the X-axis motor 42 is driven in accordance with theoutput from the sensor 163, there is a possibility in that the center ofgrip of the hand is offset in the X-direction. Also, the hand assembly16 reciprocates in the Y-direction along the vertical column 18.However, if the vertical column 18 is obliquely mounted to the rail base32, there is not only the Y-directional positional offset but also theX-directional positional offset between the lower and upper positions ofthe vertical column 18. In addition, if the sensor 167 and the detectionposition of the sensor flag 141 are offset in the rotational direction,the hand unit 130 grips the cartridge in a slanted position. When suchpositional offsets occur, it is impossible not only to correctly gripthe cartridge accommodated in the cell but also to push the cartridgeinto the cell or the accessor mount cell. Accordingly, if an accessor 14incapable of correcting such positional offset is used, it is impossibleto reduce the cell pitch, whereby the increase in the number ofcartridges to be accommodated in the library apparatus becomesdifficult.

FIGS. 59 through 62 illustrate a flow chart for explaining the operationfor the positional correction of the accessor 14 used as a carriage. Theflow chart will be described with reference also to FIG. 57 and FIGS. 63through 65.

In FIG. 63, the original point position flag 165 is accurately attachedto the accessor unit 9. The rail base 32 of the accessor 14 is providedwith the photoelectric sensor 163 for detecting the original pointposition flag 165. Also the photoelectric sensor 162 fixed on the baseof the accessor 14 is illustrated. The accessor unit 9 is provided withposition-correcting flags 910, 920 and 930 accurately fixed at positionsat which selected cells are detected.

(1) Steps S101 through S102: CPU 400 locates the X-axis, Y-axis andZ-axis at home positions at step S101. That is, CPU 400 drives theX-axis motor 42 via the motor driver 402 to locate the photoelectricsensor 163 at a position for detecting an edge of the original pointposition flag 165. Further, CPU 400 drives the Y-axis motor 46 via themotor driver 406 to locate the hand assembly 16 at a height at which thephotoelectric sensor 162 can detect the position-correcting flags 910and 920. CPU 400 drives the motor 25 to locate the photoelectric sensor167 at a position for detecting an original point of the sensor flag141. The original point of the sensor flag 141 is defined at a positiondifferent from the one at which the sensor 162 and theposition-correcting flag 910 or 920 are correctly opposite to eachother. Then, the base 28 of the hand assembly 16 is made to rotaterelative to the base 27 so that the inclination angle of the handassembly 16 is 12°. CPU 400 clears up the contents of the carriageposition-correcting table at step S102. Also, the counters 410, 412 and413 are reset.

(2) Steps S104 through S106: CPU 400 first drives the motor 25 to locatethe sensor 162 opposite to the position-correcting flag 910 (flag A).Then, the base 27 is positioned at an angle at which it is expected thatthe sensor 162 is opposite to the position-correcting flag 910. CPU 400drives the X-axis motor 42. That is, CPU 400 drives the X-axis motor 42by a standard value XNA. This standard value is given as a distance fromthe original point position flag 165. The rail base 32 is located at theX-directional position at which it is expected that the sensor 162 isopposite to the position-correcting flag 910. While maintaining thisstate, CPU 400 drives the motor 42 alone to reciprocatedly rotate. Theoptical axis of the sensor 162 reciprocatedly scans theposition-correcting flag 910 along the X-axis. While the optical axis ofthe sensor 162 reciprocatedly scans, CPU 400 reads a value on thecounter 410 at an instant when an output from the sensor 162 is ON. ThenCPU 400 stores this value in the work area 426 of the memory 416. Thestored value is a measured value XAA shown in FIG. 63.

(3) Steps S108 through S110: CPU 400 drives the motor 25 to locate thesensor 162 opposite to the position-correcting flag 920 (flag B). Thebase 27 is positioned at an angle at which it is expected that thesensor 162 is opposite to the position-correcting flag 920. Then, whilemaintaining this state, CPU 400 drives the motor 42 alone toreciprocatedly rotate. The optical axis of the sensor 162 reciprocatedlyscans the position-correcting flag 920 along the X-axis. While theoptical axis of the sensor 162 reciprocatedly scans, CPU 400 reads avalue in the counter 410 at an instant when an output from the sensor162 is ON. Then CPU 400 stores this value in the work area 426 of thememory 416. The stored value is a measured value XNB shown in FIG. 64A.

(4) Steps S112 through S116: CPU 400 calculates an average value XH ofthe measured values XNA and XNB. Then a difference between the standardvalue XNA and the average value XH is obtained. The difference is addedto the standard value XNA. A new X target value is defined by the resultof addition. CPU 400 drives the motor 42 to coincide with the new Xtarget value. A position-correcting value in the X-direction is thusobtained and stored in a correction value table in the work area 426.

(5) Steps S118 through S122: CPU 400 drives the motor 25 to locate thesensor 162 opposite to the position-correcting flag 910. The base 27 ispositioned at an angle at which it is expected that the sensor 162 isopposite to the position-correcting flag 910. That is, CPU 400 drivesthe motor 25 by a standard value ZNA. This standard value ZNA is givenby a rotational angle after the sensor 167 has detected the sensor flag141. Thereafter, CPU 400 reciprocatedly rotates the motor 25 alone. Theoptical axis of the sensor 162 reciprocatedly scans theposition-correcting flag 910 in the X-direction. While the optical axisof the sensor 162 scans, CPU 400 reads a value on the counter 413 at aninstant when an output from the sensor 162 is ON. CPU 400 stores themeasured value ZAA in the work area 426 of the memory 416. Further, CPU400 calculates a difference between the standard value ZNA and themeasured value ZAA and stores it in the work area 426 as a correctionvalue ZHA. In such a manner, a correction value of a Z-position on asurface wherein the position-correcting flag 910 is provided. This firstcorrection value in the Z-direction is stored in the correction valuetable in the work area.

(6) Steps S124 through S126: CPU 400 drives the motor 25 to locate thesensor 162 opposite to the position-correcting flag 920. The base 27 ispositioned at an angle at which it is expected that the sensor 162 isopposite to the position-correcting flag 920. That is, CPU 400 drivesthe motor 25 by a standard value ZNB. Thereafter, CPU 400 reciprocatedlyrotates the motor 25 alone. The optical axis of the sensor 162reciprocatedly scans the position-correcting flag 920 in theX-direction. While the optical axis of the sensor 162 scans, CPU 400reads a value on the counter 413 at an instant when an output from thesensor 162 is ON. CPU 400 stores the measured value ZAA in the work area426 of the memory 416. Further, CPU 400 calculates a difference betweenthe standard value ZNB and the measured value ZAB and stores it in thework area 426 as a correction value ZHB. In such a manner, a correctionvalue of a Z-position on a surface wherein the position-correcting flag930 is provided. This second correction value in the Z-direction isstored in the correction value table in the work area, is obtained.

(7) Step S128: CPU 400 calculates a new target value by adding thecorrection value ZHA to the standard value ZNA. CPU 400 locates thesensor 162 to coincide with the position-correcting flag 910.

(8) Steps 130 through 136: Then CPU 400 determines a correction valuefor a detection sensitivity of the sensor 162 in the X and Y-directionswhile maintaining the hand assembly 16 at an inclination angle of -12°.Further, CPU 400 determines a correction value for a detectionsensitivity of the sensor 162 in the Y-direction while maintaining thehand assembly 16 at an inclination angle of -5.5°. A method forobtaining these detection sensitivities will be described later. Theoptical axis of the sensor 162 is in the horizontal plane when the handassembly 16 is opposite to the position-correcting flag 910 at theinclination angle of -12°. Accordingly, since the optical axis of thesensor 162 is deviated from the horizontal plane when the inclinationangle of the hand assembly is -5.5°, it is necessary to correct thedetection sensitivity.

(9) Step 138: CPU 400 calculates a new target value by adding thecorrection value ZHB to the standard value ZNA. CPU 400 locates thesensor 162 to coincide with the position-correcting flag 920.

(10) Steps 140 through 150: Next, CPU 400 restores the inclination angleof the hand assembly 16 to -12°. CPU 400 determines a correction valuefor the detection sensitivity of the sensor 162 in the X-direction.Further CPU 400 locates the hand assembly at the inclination angel of-5.5°. Then CPU 400 determines a correction value for the detectionsensitivity of the sensor 162 in the Y-direction. A method for obtainingthese detection sensitivities will be described later. After thecorrection values for the detection sensitivity have been determined,CPU 400 restores the inclination angle to -12°.

(11) Steps S152 through S158: Next, CPU 400 detects a tilting angle ofthe vertical column 18 and determines a correction value thereof. First,CPU 400 locates the sensor 162 opposite to the position-correcting flag910. Then CPU 400 locates the sensor 162 opposite to theposition-detecting flag 930. While maintaining the Y-position of thesensor 162, CPU 400 makes the sensor 162 to reciprocatedly scan theposition-correcting flag 930 in the X-direction. While the optical axisof the sensor 162 scans, reads a value of the counter 410 at an instantwhen a detection output from the sensor 162 is ON. Then, CPU 400calculates a difference between an expected value of theposition-correcting flag 930 in the X-axis direction and the measuredvalue and recognizes the same as the positional offset between the upperand lower positions in the Y-direction. This difference is stored in thecorrection value table in the work area 426.

(12) Step 160: CPU 400 stores the stored values in the correction valuetable to the non-volatile memory 420 and completes the operation for theposition-measurement.

Next, the operation for correcting the sensitivity of the sensor will bedescribed.

FIG. 66 illustrates the relationship between the position-correctingflags 910, 920, 930 and the sensor 162. FIG. 67 is the illustration forexplaining the operation for correcting the sensitivity of the sensor.

In the drawings, each of the position-correcting flags 910, 920 and 930is constituted by a white section 950 of a cross-shape and blacksections 952a through 952d. The white section 950 of a cross-shapeincludes a part 950a extending in the X-direction and a part 950bextending in the Y-direction.

FIGS. 68 and 69 is a flow chart of the operation for correcting thesensitivity of the sensor in the X-direction.

(1) Steps S162 through S166: CPU 400 determines that a center O of thereference flag 910 is a temporary target position of the optical axis ofthe sensor 162. Then, CPU 400 adds a difference between the temporarytarget position and a scanning starting point on the flag 910 to thetemporary target position to obtain a target position for thepositioning operation. The target position is within the black section952d. CPU 400 moves the sensor 162 to the target position.

(2) Steps S162 through S166: CPU 400 moves the sensor 162 in thescanning direction 1 in the X-direction (see FIG. 67) while maintainingthe Y-position, and determines whether or not an output from the sensor162 is ON. The value of the counter 420 at an instant when the outputfrom the sensor 162 is ON is stored in the work area 426 as a measured Xvalue Xa. CPU 400 continuously moves the sensor 162 in the X-direction.CPU 400 stops the X-directional movement of the sensor 162 when theoutput from the sensor 162 is OFF. The variation of the output from thesensor at that time is shown by a wave shape WA in FIG. 67.

(3) Steps S178 through S180: CPU 400 adds a difference between thecenter of the reference flag 910 which is a temporary target positionand a scanning starting point on the flag 910 to the temporary targetposition to obtain a target position for the positioning operation. Thetarget position is within the black section 952a. CPU 400 moves thesensor 162 to the target position.

(4) Steps S182 through S190: CPU 400 moves the sensor 162 in thescanning direction 2 in the X-direction (see FIG. 67) while maintainingthe Y-position, and determines whether or not an output from the sensor162 is ON. A value of the counter 420 at an instant when the output fromthe sensor 162 is ON is stored in the work area 426 as a measured Xvalue Xb. CPU 400 continuously moves the sensor 162 in the X-direction.CPU 400 stops the X-directional movement of the sensor 162 when theoutput from the sensor 162 is OFF. The variation of the output from thesensor at that time is shown by a wave shape WB in FIG. 67.

(5) Steps S192 through S194: CPU 400 calculates an average value of themeasured X values Xa and Xb. Also, CPU 400 defines the X-directional ONposition of the sensor 162 by calculation. Finally, CPU 400 stores adifference between the actual sensor-ON position and the definedsensor-ON position as an ON correction value in the correction valuetable. Thus the operation for correcting the X-directional sensitivityhas been completed.

Next, the operation for correcting the Y-directional sensor sensitivitywill be described.

FIGS. 70 and 71 illustrates a flow chart of the operation for correctingthe Y-directional sensor sensitivity.

(1) Steps S196 through S200: CPU 400 determines that a center O of thereference flag 910 is a temporary target position of the optical axis ofthe sensor 162. Then, CPU 400 adds a difference between the temporarytarget position and a scanning starting point on the flag 910 to thetemporary target position to obtain a target position for thepositioning operation. The target position is within the black section952d. CPU 400 moves the sensor 162 to the target position.

(2) Steps S202 through S210: CPU 400 moves the sensor 162 in thescanning direction 3 in the Y-direction (see FIG. 67) while maintainingthe X-position, and determines whether or not an output from the sensor162 is ON. A value of the counter 420 at an instant when the output fromthe sensor 162 is ON is stored in the work area 426 as a measured Yvalue Ya. CPU 400 continuously moves the sensor 162 in the Y-direction.CPU 400 stops the Y-directional movement of the sensor 162 when theoutput from the sensor 162 is OFF. The variation of the output from thesensor at that time is shown by a wave shape WC in FIG. 67.

(3) Steps S212 through S214: CPU 400 adds a difference between thecenter of the reference flag 910 which is a temporary target positionand a scanning starting point on the flag 910 to the temporary targetposition to obtain a target position for the positioning operation. Thetarget position is within the black section 952c. CPU 400 moves thesensor 162 to the target position.

(4) Steps S216 through S226: CPU 400 moves the sensor 162 in thescanning direction 4 in the Y-direction (see FIG. 67) while maintainingthe X-position, and determines whether or not an output from the sensor162 is ON. A value of the counter 420 at an instant when the output fromthe sensor 162 is ON is stored in the work area 426 as a measured Yvalue Yb. CPU 400 continuously moves the sensor 162 in the Y-direction.CPU 400 stops the Y-directional movement of the sensor 162 when theoutput from the sensor 162 is OFF. The variation of the output from thesensor at that time is shown by a wave shape WD in FIG. 67.

(5) Steps S228 through S230: CPU 400 calculates an average value of themeasured Y values Ya and Yb. Also, CPU 400 defines the Y-directional ONposition of the sensor 162 by a result of calculation. Finally, CPU 400stores a difference between the actual sensor-ON position and thedefined sensor-ON position as an ON correction value in the correctionvalue table. Thus the operation for correcting the Y-directionalsensitivity has been completed.

Next, the operation for correcting the Z-directional sensor sensitivitywill be described.

FIGS. 72 and 73 illustrates a flow chart of the operation for correctingthe Z-directional sensor sensitivity.

(1) Steps S232 through S236: CPU 400 determines a standard Z-position inthe Z=n direction. In this regard, n is "1" or "0". "1" is defined asthe direction to rotate the sensor rightward, while "0" is defined asthe direction to rotate the sensor leftward. First, CPU 400 determinesn=1, and then adds a difference between the standard Z-position and ascanning starting point on the flag 910 to the standard Z-position toobtain a target position for the positioning operation. CPU 400 movesthe sensor 162 to the target position.

(2) Steps 238 through 246: CPU 400 moves the sensor 162 in the scanningdirection 1 (see FIG. 67) by rotating the Z-system while maintaining theX and Y-positions, and determines whether or not an output from thesensor 162 is ON. A value of the counter 413 at an instant when theoutput from the sensor 162 is ON is stored in the work area 426 as ameasured Z value Za. CPU 400 continuously moves the sensor 162 in theY-direction. CPU 400 stops the Z-directional movement of the sensor 162when the output from the sensor 162 is OFF. The variation of the outputfrom the sensor at that time is the same as the wave shape WA in FIG.67.

(3) Steps S248 through 252: CPU 400 determines n=0, and then adds adifference between the standard Z-position and a scanning starting pointon the flag 920 to the standard Z-position to obtain a target positionfor the positioning operation. CPU 400 moves the sensor 162 to thetarget position.

(4) Steps 254 through 262: CPU 400 moves the sensor 162 in the scanningdirection 2 (see FIG. 67) by rotating the Z-system while maintaining theX and Y-positions, and determines whether or not an output from thesensor 162 is ON. A value of the counter 413 at an instant when theoutput from the sensor 162 is ON is stored in the work area 426 as ameasured Z value Zb. CPU 400 continuously moves the sensor 162 in theY-direction. CPU 400 stops the Z-directional movement of the sensor 162when the output from the sensor 162 is OFF. The variation of the outputfrom the sensor at that time is the same as the wave shape WB in FIG.67.

(5) Steps S264 through S230: CPU 400 calculates an average value of themeasured Z values Za and Zb, and stores the same in the correction valuetable as an ON position of the sensor 162 in the Z-direction. Thus, theoperation for correcting the sensitivity in the Z-direction has beencompleted.

An alternative operation for correcting the accessor position will bedescribed below.

FIG. 74 is the illustration for explaining a logical address arrangementallocated to the respective units in the library apparatus shown inFIG. 1. Frame numbers (Frame=1, 2, . . . , n) are allocated to therespective units disposed in the travelling direction of the accessor14. Side numbers (z=0, 1) are allocated to denote the respective sidesof the travelling path of the accessor 14.

As stated before, if the library apparatus 2 shown in FIG. 1 consists offour drum units 10b, each solely having a cell drum 15b, one drum unit10a shown in FIG. 4 and one drum unit 169, the following addresses willbe allocated. In this regard, the drum unit 10b shown in FIG. 1 isidentical to the drum unit 169 having the DEE magazine. The accessorunit 10a has Frame No. 1 but has no Side No. The drum unit 10a has FrameNo. 2 and Side No. 1. The drum unit 169 (10b) has Frame No. 2 and SideNo. 0. The drive unit 12b has Frame No. 3 and Side No. 1. The drive unit12c has Frame No. 3 and Side No. 0. The drive unit 12a has Frame No. 4and Side No. 0. The four drive units respectively have Frame No. 5 andSide No. 1; Frame No. 5 and Side No. 0; Frame No. 6 and Side No. 1; andFrame No. 6 and Side No. 0. Finally, the Accessor unit 7 has Frame No. 6but has no Side No..

FIG. 75 illustrates the addresses allocated to the respective drumunits. Addresses "01" through "0A" are allocated in the X-direction andthose "01" through "35" are allocated in the Y-direction.

FIG. 76 is the illustration for explaining control values for themachine controller.

A cell address map 432 stores the address map shown in FIG. 75 andcoordinates of the addresses indicated thereby. The address coordinatesare dimensions (X-coordinate and Y-coordinate) from a reference point Oof the drum unit (reference original point Fso). A cell-positionstandard value table 434 stores a coordinate value (X, Y) of ameasurement starting point shown in FIG. 78. This coordinate value (X,Y) corresponds to a distance from that of an original point from whichthe movement of the accessor 14 starts. The coordinate value of themeasurement starting point is stored as a difference from an expectedvalue stated later. In the accessor 14 of the accessor unit 7, thecoordinate value of the original point from which the movement of theaccessor 14 starts is determined by the original position flag 165 fixedin the accessor unit 7. The cell address map 432 and the cell positionstandard value table 434 are stored in the program storage area 424 ofthe RAM 416 when the program has been installed. The correspondencebetween the respective units in the library apparatus 2 stated beforeand the Frame Nos. and Side Nos. thereof is stored in part of the celladdress map 432. Further, X-directional installation intervals of therespective units are equal to a predetermined value, which also isstored in part of the cell address map 432.

A designated address table 436 stores values for defining a pivot centerof the upper hand 146 and the lower hand 148 of the hand unit 130 of theaccessor 14. A "frame position" stores Frame Nos. described withreference to FIG. 74. "X-address" and "Y-address" store coordinatevalues of cells in the drum unit described with reference to FIG. 74."Z-address" stores Side Nos. described with reference to FIG. 74. Atarget value table 438 stores target values for defining a pivot centerof the hand unit 130 on the accessor 14. "X-target value", "Y-targetvalue", and "Z-target value" are calculated from rotational pulses ofthe respective motors 42, 46 and 25. An expected value table 440 storesX-directional and Y-directional expected values. The expected valuetable 440 is used when the operation for measuring the position of theaccessor is carried out. A present value table 442 stores X-directionaland Y-directional present positions of the accessor 14. TheX-directional and Y-directional present positions correspond to thevalues of the counters 410 and 412. A position conservation table 444stores present X and Y-values at a particular instant. The X andY-positions stored in the position conservation table 444 are used whenthe operation for measuring the position of the accessor is carried out.A correction value table stores, as correction values, differencesbetween the values stored in the present position table 442 and thosestored in the position conservation table 444. These tables 436, 438,440, 444 and 446 are stored in the work area in RAM 416.

An X and Y-position correction value table 448 stores X-positioncorrection values and Y-position correction values for all the flags.The values stored in this table 448 are in the non-volatile memory 420.

FIGS. 77, 78 and 79 are the illustrations for explaining the operationof measuring the accessor position.

FIG. 77 is the illustration for explaining a coordinate system of thereference cell of the drum unit carrying the DEE magazine.

In FIG. 77, the coordinate system of the reference cell will beexplained with reference to one of seven segments of the magazine drum175 in the drum unit 169. The drum unit 169 carries magazines 200Sthrough 200V in the respective magazine racks 184a through 184d of themagazine drum 175, as explained with reference to FIG. 40. a lower rightcell 254m of each of the magazines 200S through 200V is a referencecell. A lower right end 179a of the drum unit 169 is the frame referenceoriginal point Fso. The lower right end 179a of the drum unit 169 isused as a reference point for the coupling with another unit. Acoordinate value of the reference cell 254m of the drum unit 169 isrepresented by a rectangular coordinate system having an original pointcoinciding with the frame reference original point Fso. The coordinatevalue of the reference cell 254m is represented by a coordinate value(Xs, Ys) of a center of the reference cell 254m. The coordinate values(Xs, Ys) of the centers of the reference cells 254m of the respectivemagazines 200S through 200V are represented by coordinate values on therectangular coordinate system having an original point coinciding withthe frame reference original point Fso. As stated before, the magazines200S through 200V are roughly positioned relative to a reference point169a of the drum unit 169 by means of the guide plates 186, 187, 188 and189, the projections 210 and 212, the positioning projection 214 and thepositioning holes 201a and 201b of the magazine 200.

Accordingly, a coordinate value (Xs, Ys) of an actual center of thereference cell 254m of the magazine 200 is that defined while using, asa reference, the frame reference original point Fso which is thepositioning reference point 169a.

FIG. 78 illustrates the relationship between an actual center of thereference cell and a reference center thereof.

In FIG. 78, a coordinate value (Xm, Ym) of a actual center Pp of thereference cell 254 m is apart by a distance Lx in the X-direction and adistance Ly in the Y-direction from a coordinate value (Xm, Ym) of areference point Pm of a position-correction mark 190a. These dimensionsLx, Ly are stored in part of the cell address map 432 as stated before.That is, since the position-correction mark 190a is accurately attachedto the frame 180, the coordinate value (Xm, Ym) of the reference pointPm of the position-correction mark 190a is defined while using the framereference original point Fso as a reference. The actual center Pp of thereference cell 254m is offset in the X and Y-directions from a referencecenter Ph of the reference cell 254m defined while using the framereference original point Fso as an original point. The reference centerPh of the reference cell 254m is represented by a coordinate value (Xh,Yh). The reference center Ph of the reference cell 254m is a point atwhich should exist a center of the reference cell 254m in a standardrectangular coordinate system having an original point at the positionflag 165 of the accessor unit 9. Since the library apparatus 2 isassembled by coupling a plurality of units 7, 9, 10a and 10b with eachother, there is an offset between the actual center Pp and the referencecenter Ph of the reference cell 254m. Such an offset is measured by theposition-correcting mark 190a.

FIG. 79 illustrates the relationship between the position-correctingmark and the measurement starting point.

In FIG. 79, the position-correcting mark 190a is constituted by a blacksection 450, a Y-directional white section 452 and an X-directionalwhite section 454. A reference point Pm of the position-correcting mark190a is represented by a measured coordinate value (Xm, Ym). A startingpoint (optical axis of the sensor 162) for measuring a position of theaccessor 14 is determined at a measurement starting point Pi (Xi, Yi) ofthe position-correcting mark 190a. The coordinate value (Xi, Yi) of themeasurement starting point Pi is defined by the standard rectangularcoordinate system having an original point at the position flag 165 ofthe accessor unit 9. An expected point Pe is defined as a point at whichshould exist the reference point Pm of the position-correcting mark whenthe sensor 162 moves in the X and Y-directions from the measurementstarting point Pi. In this regard, the coordinate value (Xi, Yi) of themeasurement starting point Pi is stored as a difference from thecoordinate value (Xp, Yp) of the expected value Pe in the cell-positionstandard value table 434.

The expected point Pe is represented by a coordinate value (Xe, Ye).Since errors occur in the assembly of the library apparatus 2, thecoordinate value (Xm, Ym) of the actual reference point Pm of theposition-correcting mark 190a is offset from the coordinate value (Xe,Ye) of the expected value Pe. A difference between the coordinate values(Xm, Ym) and (Xe, Ye) of the reference point Pm and the expected pointPe, respectively, become correction values. These X-correction value andY-correction value are used for correcting the offset between the actualcenter Pp and the reference center Ph of the reference cell 254m.

FIG. 80 is a flow chart for explaining the operation of the machinecontroller 351.

In FIG. 80, After the power source has been switched on, CPU 400 carriesout the initialization at step S200. In the initialization, CPU 400drives the motors 42, 46 and 25 via the drivers 402, 406 and 414 tolocate the accessor 14 at the reference position in the accessor unit 7.CPU 400 drives the motors 42, 46 and 25 of the accessor 14 so that thesensor 163 can detect the position flag 165 and the sensor 162 of thehand assembly 16 can detect the position flag 165.

At step S210, CPU 400 determines whether or not the position-correctionvalues are stored in the X and Y-position correction value table 448 inthe non-volatile memory 420. If the position-correction values are notstored, the control proceeds to step S220 at which the measurement ofthe position-correction values is carried out. After the completion ofthe process at step S220, the control proceeds to step S212.

If the position correction values are stored, the control proceeds tostep S212 at which it is determined whether or not the operation commandis present. If the operation command is received via the interface 422at step S212, the control proceeds to step S214. At step S214, CPU 400determines whether or not the operation command is a command forchecking the presence of magazine. If the answer is affirmative, thecontrol proceeds to step S216 at which it is determined whether or notthe magazine exists. If the command received at step S214 is other thanthe command for checking the presence of magazine, the control proceedsto step S218 at which the operation is carried out in accordance withthe received command. The control returns to step S212 after theoperation based on the magazine checking command or the other commandhas been completed.

FIGS. 81 through 83 illustrate a flow chart for the measurement of theposition-correction values.

(1) Steps S240 through S244: CPU 400 takes the address (Frame No. andSide No.) of a unit in the drum unit 169 on which the measurement of theposition-correction value is to be carried out into the designatedaddress table 436 If it is assumed that this drum unit 169 is the drumunit 10b shown in FIG. 74, the address of the drum unit 169 (10b) isdefined by Frame No.=2 and Side No. Z=0. Next, at step S242, CPU 400takes the address of the reference cell 254m therein. The address of thereference cell 254m is defined by a coordinate value of a cell in thedrum unit shown in FIG. 77. The reference cell 254m is positioned in thelower right corner of the respective magazine 200S to 200V. theX-address of the reference cell 254m of the magazine 200S is "04" andthe Y-address is "04".

The X-addresses of the magazines 200T through 200V are all identical tothat of the reference cell 254m of the magazine 200S; i.e., "04". While,the Y-address of the magazine 200T is "0D", that of 200U is "16", andthat of 200C is "1F". These X and Y-addresses are represented byhexadecimal numbers.

Then, at step S244, CPU 400 sets a relative position flag pointer RPF at"N=1". The value of the pointer RPF sequentially designates themagazines 200T through 200V.

(2) Steps S246 through S252: Next, CPU 400 refers to the cell addressmap 432 in accordance with the X-address "04" of the reference cell 254mof the magazine 200S designated by the pointer RPF. CPU 400 calculatesthe X-coordinate value Xh of the reference center Ph of the referencecell 254m by the X-coordinate value Xs of the frame reference originalpoint Fso, a width of the drum unit and a sum of the X-directionaldifferences of a distance from a position of the original point flag 165to the reference point 169a of the drum unit. Then, CPU 400 converts theX-coordinate value Xh to a count number for the encoder (tachometer) 404and stores the same in an internal register. In addition, CPU 400 readsa dimension Lx corresponding to a difference between the X-coordinatevalues of the expected value Pe and the reference center Ph from thecell address map 432, and subtracts the same from the X-coordinate valueXh. Further, CPU 400 subtracts the X-directional difference between acenter line of the hand unit 130 and an optical axis of the sensor 162from the X-coordinate value Xh. The X-directional difference between thecenter line of the hand unit 130 and the optical axis of the sensor 162is stored in the cell address map 432 described before. CPU 400 storesthe calculated result in the expected value table 440 as an X-coordinatevalue of the expected value Pe.

(3) Steps S254 through 260: Then, CPU 400 refers to the cell address map432 in accordance with the Y-address "04" of the reference cell 254m ofthe magazine 200S designated by the pointer RPF. CPU 400 calculates theY-coordinate value Yh of the reference center Ph of the reference cell254m by the Y-coordinate value Ys of the frame reference original pointFso and a sum of the Y-directional differences of a distance from aposition of the original point flag 165 to the reference point 169a ofthe drum unit. Then, CPU 400 converts the Y-coordinate value Yh to acount number for the encoder (tachometer) 408 and stores the same in aninternal register. In addition, CPU 400 reads a dimension Lycorresponding to a difference between the Y-coordinate values of theexpected value Pe and the reference center Ph from the cell address map432, and subtracts the same from the Y-coordinate value Yh. Further, CPU400 subtracts the Y-directional difference between a center line of thehand unit 130 and an optical axis of the sensor 162 from theY-coordinate value Yh. The Y-directional difference between the centerline of the hand unit 130 and the optical axis of the sensor 162 isstored in the cell address map 432 described before. CPU 400 stores thecalculated result in the expected value table 440 as an Y-coordinatevalue of the expected value Pe.

(4) Steps S262 through S268: CPU 400 adds the X-directional differencebetween the measurement starting point Pi and the expected point Pestored in the cell position standard value table 434 to the expected Xvalue stored in the expected value table 440 to calculate anX-coordinate of the target value for positioning the sensor 162. Then,CPU 400 adds the Y-directional difference between the measurementstarting point Pi and the expected value Pe stored in the cell positionstandard value table 434 to the expected Y value stored in the expectedvalue table 440 to calculate an Y-coordinate of the target value. Inthis regard, the target Z value represents a rotational angle of themotor 25 for positioning the hand assembly 16 opposite to a cell. Thisvalue is calculated by CPU 400 from the Z-address (z=1 or 0) stored inthe designated address table 436. CPU 400 locates the accessor 14 whichis operated as a carriage for transporting the sensor 162 at a targetposition stored in the target value table 438. That is, CPU 400 drivesthe motors 42, 46, 25 to locate the sensor 162 at the measurementstarting point Pi. CPU 400 resets the contents of the counters 410 and412 before the sensor 162 starts the travelling.

(5) Steps S268 through S276: After the sensor 162 has been positioned atthe measurement starting point Pi, CPU 400 drives the motor 42 alonewhile maintaining the motors 25 and 46 stationary to move the rail base32 along the X rail 20. Thus, the sensor 162 is made to travel from themeasurement starting point Pi to the white section 454 of theposition-correction mark 190a in the X-direction. During the travel ofthe sensor 162, CPU 400 detects an instant at which the detection outputof the sensor 162 is ON. Also the instant is detected at which thesensor 162 reaches the white section 454. CPU 400 reads a value of thecounter 410 for counting outputs from the encoder 404 when the detectionoutput of the sensor 162 is ON. The value of the counter 410 representsthe measured X value (Xm). The measured X value Xm is saved in the savedposition value table 444 as a saved X-position value. In this regard,CPU 400 renews the present position of the sensor 162 in the aid of thecounters 410 and 412 during the measurement of the position and storesin the present position value table 442. After the output from thesensor 162 has become OFF, CPU 400 interrupts the drive of the motor 42.Next, CPU 400 calculates the difference between the expected X value inthe expected value table 440 and the measured X value saved in the savedposition value table 444. This difference is stored as a correction Xvalue in the correction value table 446. CPU 400 drives the motor 42 inthe reverse direction to locate the sensor 162 at a positioncorresponding to the measured X value Xh and confirms that there is areflection from the white section 454.

(6) Steps S280 through S292: CPU 400 locates the sensor 162 at themeasurement starting point Pi. After the sensor 162 has been located atthe measurement starting point Pi, CPU 400 drives the motor 46 alonewhile the motors 42 and 25 are stationary for the purpose of moving thebase 27 along the rail guide 22. Thus, the sensor 162 travels from themeasurement starting point Pi to the white section 452 of the positioncorrection mark 190a in the Y-direction.

During the travel of the sensor 162, CPU 400 detects an instant at whichthe detection output of the sensor 162 is ON. Also an instant isdetected at which the sensor 162 has reached the white section 452. CPU400 reads a value of the counter 412 for counting outputs from theencoder 408 when the detection output of the sensor 162 is ON. The valueof the counter 412 represents the measured Y value (Ym). The measured Yvalue Ym is saved in the saved position value table 444 as a savedX-position value. After the output from the sensor 162 has become OFF,CPU 400 interrupts the drive of the motor 46.

Next, CPU 400 calculates a difference between the expected Y value inthe expected value table 440 and the measured Y value saved in the savedposition value table 444. This difference is stored as a correction Yvalue in the correction value table 446. CPU 400 drives the motor 46 inthe reverse direction to locate the sensor 162 at a positioncorresponding to the measured Y value Yh and confirms that there is areflection from the white section 452.

(7) Steps S296 through S300: CPU 400 determines after the operation atstep 292 has completed whether or not a value of the relative positionflag pointer RPF is a maximum. In other words, it is determined whetheror not the positional measurement of the position-correcting mark 190din the magazine 200V has been completed.

In the magazine drum 175 of the drum unit 169, four magazine shelves184a through 184d are mounted. Accordingly, CPU 400 determines whetheror not the value of the pointer RPF is "N=4". If the value of thepointer RPF does not coincide with the maximum, 1 is added to the valueof the pointer RPF. Then the control returns to step S246 at which theposition measurement of the next position-correcting mark is carriedout.

If the value of the pointer RPF coincides with the maximum value, thecorrection values of the respective position-correcting marks 190athrough 190d are stored in the X and Y-position correction table 448 inthe non-volatile memory.

Thus the position measurement has been completed and the control returnsto step 212 to wait for an operation command.

The position measurement described above was carried out on the drumunit having the DEE magazine but may be carried out on the drum unithaving no DEE door shown in FIGS. 17 through 22. In the latter case, theposition-correcting mark may be provided on the pillar 686a or the base654a of the drum unit 10A.

As stated above, according to the library apparatus 2, since theposition measurement between the accessor unit 9 and the drum unit 10 iscarried out, it is possible to absorb the assembly errors generated whenthe respective units are coupled to each other. Thereby, since thesevere assembly accuracy is unnecessary a reduction of the assembly timeperiod is possible.

FIGS. 84 through 86 show a flow chart of the operation for checkingwhether or not the magazine is present.

1 Steps S400 to S406: CPU 400 takes an address (Frame No. and Side No.)of the drum unit 169 into the designated address table 436, on whichunit is carried out the operation for checking whether or not themagazine is present. It is assumed that the address of this drum unit169 is defined by Frame No. 2 and Side No. Z=0 similarly to the positionmeasurement operation. Then, an address of the reference cell 254m istaken into CPU 400. The address of the reference cell 254m is defined bythe coordinate value of a cell in the drum unit shown in FIG. 22. Thereference cell 254m is positioned at a lower right zone of each of themagazines 200S through 200V. The reference cell 254m of the magazine200S has the X-address of "04" and the Y-address of "04".

CPU 400 reads the X-correction value and the Y-correction value withreference to the X-position and Y-position correction table 448 in thenon-volatile memory 420 and stores the same in the internal register.CPU 400 sets the magazine flag pointer MZP to be "N=1". According tothis value of the pointer MZP, the magazines 200T through 200V aresequentially designated.

2 Steps S408 to S420: Next, CPU 400 refers to the cell address map 432based on the X-address "04" of the reference cell 254m of the magazine200S designated by the pointer MZP. CPU 400 obtains the X-coordinatevalue Xh of the standard center position Ph of the reference cell 254mby a sum of the X-axis value (Xs) from the frame reference originalpoint Fso, a widthwise dimension of the drum unit, the X-directionaldifference between the original point flag 165 and the reference point169 of the drum unit.

The X-coordinate value Xh is converted to the number to be counted bythe encoder (tachometer) 404, which is saved in the internal register.Then, the X-correction value read from the table 448 is added thereto.In addition, the displacement to a position 230 at which the presence ofthe magazine is checked is added. Further, the X-directional differenceis added, between a pivot center of a hand of the hand unit 130 and theoptical axis of the sensor 162. The calculated result is stored in thetarget value table as a target X value.

The position 230 at which the presence of the magazine is checked is onthe surface of the metallic plate 224 for mounting the grip 204 of themagazine 200 shown in FIG. 32. This metallic plate 224 is made, forexample, of stainless steel having a surface capable of reflecting thelight emitted from the sensor 162. The above-mentioned value to be addedfor correcting the displacement to the position 230 is preliminarilystored in the cell position standard value table 434.

The magazine 200 is formed of metal such as stainless steel. The storedvalue to be added and a distance in the actual magazine exactly coincidewith each other. Therefore, it is possible to reduce the probability oferroneously checking the presence of magazine, compared with a magazineof resinous material made through a molding process and thus having apoor dimensional accuracy.

Next, CPU 400 refers to the cell address map 432 based on the Y-address"04" of the reference cell 254m of the magazine 200S designated by thepointer MZP. CPU 400 obtains the Y-coordinate value Yh of the standardposition center of the reference cell 254m by a sum of the Y-coordinatevalue (Ys) defined by the frame reference original point Fso and theY-directional dimensional difference between the original point positionflag 165 and the reference point of the drum unit 169a.

CPU 400 converts this Y-coordinate value Yh to the number to be countedby the encoder 408 and saves the same in the internal register. Further,CPU 400 reads the Y-correction value and adds the same to theY-coordinate value Yh. Also, CPU 400 adds the Y-directional differencebetween the center line of the hand unit 130 and the optical axis of thesensor 162 to the Y-coordinate value Yh, the result of which is storedin the target value table 438 as the target Y-value.

As described above, CPU 400 adds the predetermined position-correctionvalue when the coordinate value is obtained for checking whether or notthe magazine is present. Accordingly, it is possible to correctly detectwhether or not the magazine is present.

2 Steps S422 to S424: CPU 400 locates the sensor 162 at a positioncorresponding to the target value stored in the target value table 438.The motors 42, 46 and 25 are driven by CPU 400 to locate the sensor 162at the detection position 230. CPU 400 determines whether or not thesensor 162 is located at the position 230 at which the operation forchecking whether or not the magazine is present is executed, based onthe values in the counters 410 and 412.

3 Steps S426 to S436: After the sensor has been located at the detectionposition 230, CPU 400 observes an output from the sensor 162. If theoutput from the sensor 162 shows that there is no reflection, CPU 400resets a flag representing the presence of magazine 200S in thenon-volatile memory 420. On the contrary, if the output from the sensor162 shows that there is a reflection, CPU 400 sets a flag representingthe presence of magazine 200S (i.e., the value "1" is set).

CPU 400 determines whether or not the value of the pointer MZP coincideswith "4" representing the maximum number of magazine to be mounted. Ifthe answer is negative, CPU 400 adds "1" to the pointer MZP and executesthe operation defined at step S408. On the contrary, If the answer isaffirmative, CPU 400 finishes the detection operation, and informs thesame to the controller 388 via the interface control portion 422.

If the exchange of DEE magazines in the other cell segments of themagazine drum 175 has been completed, the accessor controller 388executes the following operation:

The accessor controller 388 issues a command to the drum controller235-1 to locate the next cell segment 17 of the cell drum 15a at aposition in front of the accessor 14. On the other hand, the controller388 issues a command to CPU 400 via the interface control portion 422 tocheck whether or not the magazine is present through steps shown inFIGS. 84 through 86.

The accessor controller 388 obtains information via CPU 150 in the drumunit 169 whether or not the exchange of DEE magazines 200 has beenfinished. That is, CPU 150 in the control circuit 90 provided in thedrum unit detects the opening of DEE door 64. Simultaneously therewith,CPU 150 detects the cell segment of the cell drum 15a located in frontof the DEE door 64. CPU 150 informs the cell segment number to theaccessor controller 388 via the interface control portion 156.

The accessor controller 388 can discriminate the magazine shelf in whichthe DEE magazine is present from that in which the magazine is notpresent by means of the magazine presence flag. The accessor controller388 does not execute the operation for storing cartridges in themagazine shelf in which the magazine 200 is not mounted when thecartridges are stored in the drum unit 169. Also, the accessorcontroller 388 can prevent the operation from being carried out, fortaking out the cartridge from the magazine shelf in which the magazineis not present.

The description was made solely on the embodiments wherein a magnetictape cartridge of Type 13480 is used, but the present invention shouldnot be restricted thereto. The present invention may be applied to anyother library apparatuses having cells for accommodating an other typeof magnetic tape cartridge, an optical disk cartridge or others.

Also, according to the above embodiments, the accessor was of an X-Ymotion mechanism type. However, it is possible to use variousmodifications thereof; for example, the accessor may be of a Y-θ motionmechanism type. In the latter case, the accessor will be accommodated inthe interior of a cylindrical cell drum.

What is claimed is:
 1. A library apparatus comprising:a cell unitincluding a shelf with a plurality of cells for storing cartridgestherein; a drive unit including processing means for carrying outrecording/reading of information to cartridges in the library apparatus;an accessor unit including a transporting mechanism for transportingcartridges between the cells and the processing means; passage unitsincluding a generally horizontally extending guide member for guidingthe transporting mechanism, said guide member extending through each ofsaid passage units; separate box shaped housings for each of said cellunits, said drive unit, said accessor unit, and said passage units, saidbox shaped housings each having connecting means for aiding connectionto and alignment with a corresponding one of said box shaped housings;and coupling means for coupling the box shaped housings of the cellunit, the drive unit, and the accessor unit with the box shaped housingsof the passage units by connecting the connecting means of the cellunit, the drive unit, and the accessor unit with the connecting means ofthe passage units.
 2. A library apparatus as defined by claim 1, whereinthe accessor unit has a mark for defining a reference position and thetransporting mechanism has a sensor for detecting the mark, and whereinthe library apparatus further comprises means for correcting apositional error of the transporting mechanism relative to the cell unitor the drive unit, in accordance with the detection output from thesensor.
 3. A library apparatus as defined by claim 1, wherein the cellunit comprises a rotary drum with a plurality of cells and rotatable onits axis and a motor for rotating the rotary drum.
 4. A libraryapparatus as defined by claim 3, wherein the cell unit comprises anupper drum located above the rotary drum and rotatable with the rotarydrum.
 5. A library apparatus as defined by claim 4, wherein the rotarydrum and the upper drum are constituted by a polyhedron body having aplurality of lateral sides, on each of which are arranged the cells, andthe respective sides of the rotary drum and the upper drum are arrangedin the same planes.
 6. A library apparatus as defined by claim 5,wherein the cell unit has a housing for accommodating the rotary drum,which has a wheel on a top surface thereof for rotatably holding theupper drum.
 7. A library apparatus as defined by claim 5, wherein theplurality of cells are arranged on the respective side in a firstdirection, and the library apparatus comprises optical detection meansfor detecting the projection of the cartridge from the cell comprising alight emitting element and a light receiving element having an opticalaxis extending in the first direction.
 8. A library apparatus as definedby claim 7, wherein the library apparatus further comprises cleaningmeans for cleaning the optical detection means, means provided on therotary drum for locating the cleaning means at a cleaning position andmeans for moving the cleaning means to a retreated position.
 9. Alibrary apparatus as defined by claim 8, wherein the transportingmechanism comprises a gripper mechanism for gripping the cartridge, amotor for driving the transporting mechanism, means for supplyingelectric power to the motor, and a brake mechanism for inhibiting themovement of the transporting mechanism when the power supply to themotor is interrupted and for releasing the same when the power issupplied.
 10. A library apparatus as defined by claim 9, wherein thetransporting mechanism comprises a Y-axis transportation mechanism formoving the gripper mechanism, a Z-axis transportation mechanism forrotating the gripper mechanism in a plane transverse to the verticaldirection and an X-axis transportation mechanism for moving the Y-axistransportation mechanism in the direction transverse to the verticaldirection, whereinthe X-axis transportation mechanism comprises a basefor holding the Y-axis transportation mechanism, a rail for guiding thebase, and a roller for holding the base to be slidable along the rail;the roller being supported by the base to be located outside of a radiusof rotation of the gripper mechanism caused by the Z-axis transportationmechanism.
 11. A method for assembling a library apparatus comprising acell unit including a storage shelf with a plurality of cells forstoring cartridges therein, a drive unit including processing means forcarrying out the recording/reading of information to the cartridges, anaccessor unit including a transporting mechanism for transporting thecartridges between the cells and the processing means, and passage unitsincluding a generally horizontally extending guide member for guidingthe transporting mechanism, wherein said guide member extends througheach of the passage units, the method comprising the steps of:housingthe cell unit, the drive unit, the accessor unit, and the passage unitsin separate box shaped housings, each of said box shaped housings havingconnecting means for connecting to and aligning with a corresponding oneof said box shaped housings; coupling the box shaped housings ofcorresponding passage units with the box shaped housing of cell unitthrough the respective connecting means of the corresponding passageunits and the cell unit; coupling the box shaped housings ofcorresponding passage units with the box shaped housing of the driveunit through the respective connection means of the correspondingpassage units and the drive unit; coupling the box shaped housing ofcorresponding passage units with the box shaped housing of the accessorunit through the respective connection means of the correspondingpassage units and the accessor unit.
 12. A library apparatus with a cellunit including a plurality of cells for accommodating memory mediatherein, said cells comprising:a rightside rack including a right-sidesurface and a left-side surface, the leftside surface of the right-siderack having a plurality of shelf plates; a leftside rack including aright-side surface and a left-side surface, the rightside surface of theleft-side rack having a plurality of shelf plates; and an intermediaterack including a right-side surface and a left-side surface, both theright-side and the left-side surfaces of the intermediate rack having aplurality of shelf plates; wherein each of the plurality of cells of thecell unit are formed by a combination of two shelf plates chosen fromthe shelf plates of the right-side rack, the left-side rack, and theintermediate rack.
 13. A library apparatus as defined by claim 12,whereineach of the rightside rack, the leftside rack and theintermediate rack is molded in resin as a one piece body to have a backplate, a plurality of shelf plates projected from the front side of theback plate, and positioning projections projected from the back side ofthe back plate, and the shelf has a plate-like member with holesengageable with the positioning projections; the rightside rack, theleftside rack and the intermediate racks being mounted to the plate-likemember with screws while engaging the positioning projections with theholes.
 14. A library apparatus as defined by claim 13, wherein theplurality of shelf plates are projected from the back plate at the sameangle.
 15. A library apparatus as defined by claim 14, wherein theleftside rack and the rightside rack are attached at the right and leftends of the plate-like member, respectively, and two of the intermediateracks are attached between the leftside and rightside racks at the samedistance therebetween, so that three rows of cells are formed.
 16. Alibrary apparatus as defined by claim 1, wherein the cell unitcomprises:a plurality of cells capable of accommodating a plurality ofcartridges and a rightside rack, a leftside rack and intermediate racksfor defining the plurality of cells.
 17. A library apparatus as definedby claim 16, whereineach of the rightside rack, the leftside rack andthe intermediate rack is molded in resin as a one piece body to have aback plate, a plurality of shelf plates projected from the front side ofthe back plate, and positioning projections projected from the back sideof the back plate, and the shelf has a plate-like member with holesengageable with the positioning projections; the rightside rack, theleftside rack and the intermediate racks being mounted to the plate-likemember with screws while engaging the positioning projections with theholes.
 18. A library apparatus as defined by claim 17, wherein theplurality of shelf plates are projected from the back plate at the sameangle.
 19. A library apparatus as defined by claim 18, wherein theleftside rack and the rightside rack are attached at the right and leftends of the plate-like member, respectively, and two of the intermediateracks are attached between the leftside and rightside racks at adistance therebetween, so that three rows of cells are formed.
 20. Alibrary apparatus as defined by claim 1, wherein the cell unit has astorage shelf for accommodating cartridges in separate cells and amagazine shelf with a mounting area for accommodating a portablemagazine in a detachable manner, and a plurality of cells are formed inthe magazine by a rightside rack, a leftside rack and intermediateracks.
 21. A library apparatus as defined by claim 20, whereineach ofthe rightside rack, the leftside rack and the intermediate rack ismolded in resin as a one piece body to have a back plate, a plurality ofshelf plates projected from the front side of the back plate, andpositioning projections projected from the back side of the back plate,and a plate-like member is provided on the back side of a housing of themagazine, having holes engageable with the positioning projections; therightside rack, the leftside rack and the intermediate racks beingmounted to the plate-like member with screws while engaging thepositioning projections with the holes.
 22. A library apparatus asdefined by claim 21, wherein the plurality of shelf plates are projectedfrom the back plate at the same angle.
 23. A library apparatus asdefined by claim 22, wherein the leftside rack and the rightside rackare attached at the right and left ends of the plate-like member,respectively, and two of the intermediate racks are attached between theleftside and rightside racks at a distance therebetween, so that threerows of cells are formed.
 24. A library apparatus as defined by claim20, wherein the magazine shelf is provided with a positioning means forlocating a cell of the magazine at a position at which the cell can betreated by the transporting mechanism in a same manner as in a cell ofthe storage shelf when the magazine is mounted to the mounting area ofthe magazine shelf.
 25. A library apparatus as defined by claim 20,wherein means is provided, for determining whether or not the magazineis present in the mounting area of the magazine shelf.
 26. A libraryapparatus as defined by claim 20, wherein a door is provided on ahousing of the cell unit in front of the magazine shelf, for theentry/exit of the magazine relative to the mounting area.
 27. A libraryapparatus as defined by claim 20, wherein means is provided in themounting area of the magazine shelf, for determining whether or not acartridge is present in the cell of the mounted magazine.
 28. A libraryapparatus as defined by claim 20, wherein the cell unit comprisesmagazine forming a plurality of cells, the magazine being formed by arightside rack, a leftside rack and intermediate racks for defining theplurality of cells.
 29. A library apparatus defined by claim 28,whereineach of the rightside rack, the leftside rack and theintermediate rack is molded with resin as a one piece body to have aback plate, a plurality of shelf plates projected from the front side ofthe back plate, and positioning projections projected from the back sideof the back plate, and a plate-like member is provided on the back sideof a housing of the magazine, having holes engageable with thepositioning projections; the rightside rack, the leftside rack and theintermediate racks being mounted to the plate-like member with screwswhile engaging the positioning projections with the holes; and theplate-like member further has holes and is attached to the drum unit byby the engagement of the holes with projections provided on a back panelof the drum unit.
 30. A library apparatus as defined by claim 29,wherein the plurality of shelf plates are projected from the back plateat the same angle.
 31. A library apparatus as defined by claim 30,wherein the leftside rack and the rightside rack are attached at theright and left ends of the plate-like member, respectively, and two ofthe intermediate racks are attached between the leftside and rightsideracks at a distance therebetween, so that three rows of cells areformed.
 32. A library apparatus as defined by claim 20, wherein acartridge carries a bar code label thereon, and the cell unit has a barcode reader for reading the bar code label carried on the cartridgestored in the cell of the magazine mounted in the mounting area of themagazine shelf.
 33. A library apparatus as defined by claim 32, whereinthe bar code reader is detachable/attachable.
 34. A library apparatus asdefined by claim 33, wherein a door is provided on the housing of thecell unit located in front of the magazine shelf.
 35. A libraryapparatus as defined by claim 34, wherein the housing comprises:areference bar code representing a reference position for reading the barcode label, means for displacing the bar code reader in the arrangementdirection of cells in the storage shelf, means for detecting a positionof the reference bar code, and means for controlling the displacementmeans in accordance with the detection outputs from the detection means.36. A library apparatus as defined by claim 35, wherein the housingfurther comprises means for detecting whether or not a cartridge ispresent in the cell of the storage shelf in accordance with the outputsfrom the bar code reader.
 37. A library apparatus as defined by claim32, whereinthe cell unit has a rotary drum rotatable on its axis, therotary drum has a plurality of lateral sides; a plurality of cellsformed in a storage shelf provided on the respective lateral side beingarranged on the lateral side along the drum axis; and there are meansfor displacing the bar code reader parallel to the drum axis, means forcontrolling an angular position of the rotary drum so that the bar codecarried on the cartridge stored in the cell is located at a position infront of the reading position of the bar code reader, and means forchanging the reading position of the bar code reader in accordance witha position, on the lateral side, of the cell located in front of thereading position of the bar code reader.
 38. A method for making a cellunit including a plurality of cells for accommodating memory mediatherein, the method comprising the steps of:forming a single piecerightside rack including a left-side surface with a plurality of shelfplates and a right-side surface; forming a single piece leftside rackincluding a right-side surface with a plurality of shelf plates and aleft-side surface; forming a single piece intermediate rack including aright-side surface with a plurality of shelf plates and a left-sidesurface with a plurality of shelf plates; and placing the intermediaterack between the single piece rightside rack and the single pieceleftside rack such that said rightside rack, said leftside rack and saidintermediate rack cooperate to form a plurality of cells wherein eachcell is formed by a combination of two shelf plates chosen from theshelf plates of the rightside rack, the leftside rack, and theintermediate rack.
 39. A library apparatus comprising:a cell unitaccommodating storage media therein; a drive unit for reading/writing tothe storage media; and an accessor for transporting the storage mediabetween said drive unit and said cell unit, wherein said cell unitcomprisesa storage shelf for accommodating cartridges in separate cells;a magazine shelf with a mounting area for accommodating a portablemagazine in a detachable manner, a plurality of cells being formed inthe magazine by a rightside rack, a leftside rack and at least oneintermediate rack, a housing; a door in said housing for accessing saidmagazine shelf; a reference bar code representing a reference positionfor reading the bar code; a bar code reader; means for displacing areading direction of the bar code reader in the arrangement direction ofcells in the storage shelf; means for detecting a position of thereference bar code; and means for controlling the means for displacingin accordance with information provided by the means for detecting. 40.A method for assembling a library apparatus comprising the stepsof:positioning a reference cell unit having a box shaped housing;coupling passage units having box shaped housings to multiple sides ofthe housing of the reference cell unit, using the height of the housingof the reference cell unit as a guide to position the passage units;coupling an accessor unit having a box shaped housing to the box shapedhousing of one of said passage units, using the height of the box shapedhousing of one of said passage units as a guide to position the accessorunit; respectively coupling separate cell units having box shapedhousings to the box shaped housings of the one of said passage units anda second one of said passage units using the height of the box shapedhousings of the respective passage units as a guide to position the cellunits; and coupling a drive unit having a box shaped housing to said boxshaped housing of said reference cell unit.